EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: Picuino on March 09, 2023, 06:16:47 pm
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The problem is that electrical energy and electrical power are interrelated concepts.
Electrical power can be defined as voltage times current, but that does not explain what it is. It can also be defined more intuitively as the amount of energy consumed per second.
Electrical energy on the other hand is defined as the total work done or the total heat generated, but its formula is power times time.
It seems difficult to explain one concept without the other. They must be explained at the same time, but you have to start somewhere.
I remember that I had a hard time understanding these two concepts at first because they were similar and related.
How would you explain these two concepts to someone who does not know anything about electrical power and energy?
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Nobody does it better than Bill Beaty. (http://amasci.com/ele-edu.html) Just gotta get past the 1990s' Geocities page design. :)
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Any new concept is very hard to grasp, because… it is a new concept. So far the only available is letting brain deal with it for long enough.
If only useful analogy is needed, the situation is much simpler. Compare energy to water stored in a container and then power becomes water flow into or from the container.
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This might be of some help (at least to get started, love Eugene Khutoryansky's visual animations). Ask a physicist...
https://www.youtube.com/watch?v=u4FpbaMW5sk (https://www.youtube.com/watch?v=u4FpbaMW5sk)
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From your other thread, it seems this is a school exercise/lesson, right?
A good way of visualising this is using light.
Show an LED with a 1 ms flash. That would be power (W). For ease, pretend it's 1 V, 1 A
Then show it shining for one second. That would be energy (J). Expanding that to a minute or longer is easy for further explanation on how power accumulates to energy.
Explaining that the first flash should be imagined even shorter is not that hard.
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You could start with mechanical energy and power, from which the concepts of electrical energy and power are derived.
"Work" is the product of force times distance (where the distance is measured in the same direction as the force).
"Energy" is defined as the "capability to do work" and has the same units.
So, if you lift a 1 kg weight against 9.8 m/s2 gravitational acceleration, by a change in height of 10 m, you do 1 x 9.8 x 10 = 98 J of work, applying 9.8 N of force during the lift.
After that, you have 98 J of "potential energy" in the system, which can be used in a contraption to do other work, such as lifting 10 kg by 1 m, through a suitable mechanism, when dropping the weight through gravity.
If you accomplished the lift in 4.9 s, the "power" applied during that time was 9.8/4.9 = 2 N/s = 2 W.
In non-technical language, the words "energy", "force", and "power" are often confused.
In technical language, power always means the rate of energy per time.
Electrically, work and energy are defined as the product of voltage and charge: W = Q x V.
Since current I is the rate of charge per time, the power becomes P = I x V.
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The above video is very explanatory. It is quite good.
My problem is choosing in what order and how to explain the concepts to high school students.
The formulas I want them to learn are:
P = V - I
P = Electrical power in Watts
I = Current in Amperes
V = Voltage in Volts
E = P - t
E = Energy in Joules or in kilowatts - hour
P = Power in Watts or in kilowatts
t = Time in seconds or in hours
First I wanted to explain the power formula and then the energy formula both in separate units. The problem is that the power formula is not intuitive nor does it really explain what power is.
I have asked ChatGPT and every time it prefers to explain energy first and then power.
I could do the following:
1st Write a introduction to energy and power. Explain intuitively what each is. Where can we find more or less energy (fuel tank, battery, etc) and where can we find more or less power (electric motors, light bulbs, etc) and relationship between the two concepts. For example a very powerful car will consume little energy if it travels few kilometers, while a not very powerful car will consume more energy if it travels many more kilometers. Energy as total work done while power is the speed at which the work is done.
2º Explain the formula and exercises of electrical energy calculation. Relate it to the cost of the electric bill.
3º Explain the formula and exercises of electric power calculation.
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Electrical power can be defined as voltage times current, but that does not explain what it is. It can also be defined more intuitively as the amount of energy consumed per second.
No. Both are wrong. Power is not only electrical, and it's not only consumed.
Take a physics book and use the same definition as in the books. Power is defined as the ratio between energy and time, 1W = 1J/1s, or in words, power is about how much energy is exchanged in a unit of time. It's the "energy debit" in an energy transfer, in layman words. Can be either produced or consumed, can be electrical, mechanical, etc.
My advice would be to take inspiration from the already existing physics book. Don't try to "dumb down" the definition, this will only add confusion for your students.
After all, nobody knows what energy, or time, or power is. We just learn how to operate with their current definitions. (though, don't tell that to your students, it'll make their subconscious mind to reject any further learning about such unknowns)
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Energy is not that ineffable, when one starts from energy in mechanical contexts as defined above for a simple system, and then generalizes it to other forms of energy and introduces conservation.
Despite the fact that we can measure time more accurately than anything else, it does remain elusive in philosophy, but everyone experiences it.
Again, one must use the standard definitions in technical discussion, and avoid the confusion of terms in common or non-technical usage.
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The concept of energy can be explained with an analogy that everyone can understand: money. Then, power can be explained as how much money per unit of time can be spent or earned.
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I don't know, depending on their age, kids and youngsters don't understand money. Often adults don't understand money either. Money are not real, they are a measure of people confidence in a government. It's a dangerous analogy, because money can change their value over night, while energy is always conserved, money can be made out of nothing, from speculation or from gambling, while energy doesn't work that way, and so on.
The danger of using an analogy with an absolute beginner (about money, or water flow, or who knows about what else), is that they don't know what to keep from as valid from the analogy, and what to discard (or doesn't hold). For someone that is not a beginner, it's easy to make use of an analogy, because the expected outcome is already known.
To be constructive, I would probably start from mechanical power, which is work over time, while work, in the most intuitive way is displacement (or dragging) of a force. Now, once this definition is accepted extend it to dragging charges in a given unit of time, similar as in the physics book.
After it comes the notion of current (which includes the time in it), and thus arrive to P=U*I (where neither time nor energy are obvious, and it is correct for DC only, doesn't hold for AC).
However, I am not a teacher, only talking from my own frustrations during the schooling years. And that was, many, many moons ago, when there was no Powerpoint slides, no PCs and no Internet.
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I don't know, depending on their age, kids and youngsters don't understand money. Often adults don't understand money either. Money are not real, they are a measure of people confidence in a government.
Money can be replaced by a certain type of resource, whatever is easy to understand by the audience. For gamers: spice in Dune 2 players. Gold in nearly any strategy game. Food in the poorest countries. Energy and resource are synonyms in this context.
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For students around the age of 14 I think they already have enough working knowledge of what energy is. I will start there.
1st I will start by introducing the most common forms of energy:
Mechanical (kinetic and potential) energy.
Heat energy
Radiant energy (light, microwaves, infrared, etc.)
Atomic energy (uranium, plutonium, etc.)
Chemical energy (food, gasoline, batteries, etc.)
Electrical energy (more complicated to understand in essence, but very intuitive because it can be easily converted into almost all of the above).
2nd how energy can be transformed from one form to another and in the end it ends up as heat, which is the most degraded form of energy.
Here I will take the opportunity to recall that electrical receivers transform electrical energy into other types of energy and that electrical generators transform other types of energy into electrical energy.
3rd energy sources
Various energy sources such as radiant from the sun (which comes from nuclear), wind, tidal, geothermal, hydraulics (a type of mechanical potential energy), nuclear or fossil energies (a form of chemical storage of the sun's energy from millions of years ago).
How electricity is simply a mode of transporting energy from sources to receivers in homes and businesses.
4th here I think I have to introduce the concept of power, in order to be able to use the formulas later.
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My suggestion would be to move electrical energy discussion to the second line, following mechanical energy.
Heat and radiant energy are more complicated.
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It is just a way of presenting all forms of energy so that the whole allows us to have an intuitive idea of what energy is. I do not intend to define energy exactly, nor do I intend to go in depth about each of the forms of energy. I am content that they know how to recognize it in the world around us and that they know that electricity is a vector, like a belt that transports energy.
Edit: Also important is the concept of energy transformation. It never disappears, it transforms from one type to another.
In a swing: from potential to kinetic and vice versa.
And that in the long run it always ends up being transformed into heat.
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... ...
How would you explain these two concepts to someone who does not know anything about electrical power and energy?
It would be helpful to know what is your target audience. High School kids interested in electronic? Grade school kids?
Leaving that unanswered question alone for the moment, I agree with RoGeorge's earlier reply: "Take a physics book and use the same definition as in the books." That said, to really understand the definition, an analogy to leverage preexisting understanding will help the audience grasp the concepts quicker, and understanding the concepts is the foundation to understand the actual definition.
This is one analogy I've used that I found useful. In my case, my audience is last year of high school and first year of college types, non-science major but needing to understand enough to pass a 100 level basic Physics course.
> Energy is like money. Pretend you work on a project. You are paid to work. Money makes the wheel goes around.
>> Energy = money = capacity to do work.
> The "year long project" is valued at $1million; your wage is $10/hour for 20 "5x8" weeks at the start of that project. So that $1 million is not very meaningful to you. However, you know you are working for 5 days each week and 8 hours a day, that makes 40 hours a week and 20 weeks total. Net is 10*40*20, you make $8,000.
>> $8000 = total available for you to do work: your available energy
>> 10/hour = $ for you per unit time: "power"
Now you can latch on to that to dig deeper:
> Tax, is a good source to discuss entropy and efficiency of energy (money) exchange.
> Rounding is a good way to touch on quantization. How far down can you split a dollar before it becomes meaningless? Is $0.000001 meaningful in any transaction in our macro-world? In our every day life, money is quantize down to cents. Nature has it's own "cents" in energy exchange.
Most audience can understand total cost vs monthly payment. But the increase in Lease vs Buy intruded into that understanding. Otherwise, monthly payment vs total cost is another way to explain that energy v power. Once the audience understand the basic concept, then, bring in the real physics definition.
Where appropriate (depending on audience and their end goal), one may need to explain how definitions in Physics changes as our understanding of Physics improves.
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The problem is that electrical energy and electrical power are interrelated concepts.
Electrical power can be defined as voltage times current, but that does not explain what it is. It can also be defined more intuitively as the amount of energy consumed per second.
Electrical energy on the other hand is defined as the total work done or the total heat generated, but its formula is power times time.
It seems difficult to explain one concept without the other. They must be explained at the same time, but you have to start somewhere.
I remember that I had a hard time understanding these two concepts at first because they were similar and related.
How would you explain these two concepts to someone who does not know anything about electrical power and energy?
Do not limit the discussion to electrical energy and electrical power.
You need to consider energy (and power) in general.
One of the earliest breakthroughs in physics was determining the equivalence of energy in all its different forms, leading to the law of conservation of energy.
One of the defining experiments was churning water in a well insulated bucket, and confirming that the mechanical energy fed in was matched by the temperature rise of the water.
From there you can verify that the electrical energy fed in from a heating element is also matched by the temperature rise of the water, and thus mechanical energy (force times distance) is equivalent to electrical energy (voltage times current times time).
You can get further into thermodynamics and consider the difference between work and heat, and then the concept of "free" energy, but this tends to become difficult to explain at an elementary level.
In summary, it is not "electrical" energy and "electrical" power, it is simply energy and power, of which the electrical version is just one of the forms. If you do not explain that concept, you will have completely failed your audience.
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Leaving that unanswered question alone for the moment, I agree with RoGeorge's earlier reply: "Take a physics book and use the same definition as in the books." That said, to really understand the definition, an analogy to leverage preexisting understanding will help the audience grasp the concepts quicker, and understanding the concepts is the foundation to understand the actual definition.
Sears Zemansky:
Start by defining "work" in detail. Then he defines, in detail as well, kinetic and potential energy.
In another chapter he talks about heat as a form of energy, also in detail without a concrete definition.
In another chapter he talks about electrical potential energy.
I cannot go into that detail to finish talking about electrical energy.
Paul A. Tipler:
Like the previous one, it begins by defining work and kinetic energy in detail.
Book of last year of High School:
Nor does it give a definition of energy. It says that it is the capacity of a body to carry out transformations. One of these transformations is that it can do work.
Wikipedia:
Energy is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of heat and light.
The law of conservation of energy states that energy can be converted in form, but not created or destroyed.
The unit of measurement for energy in the International System of Units (SI) is the joule (J).
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Outrageous the last 2 definitions, if not dead wrong, but I'm not a physicist.
Also, to me they clarify as much as a marketing blurb, "recognizable in the performance of work" almost shut down my brain and put me to sleep. :-//
AFAIK energy is introduced as work. As in physical effort kind of work. By definition, work is force multiplied with displacement. If you have a 1 Newton weight and you lift it 1 meter, you'll need 1 Joule of energy.
To exemplify force, put them to keep a pencil in hand. Then put them to keep in hand a big stack of books. Feel the weight? That's more force.
To exemplify work, or energy, put one student to lift a pencil from the floor. That should be easy. Now put the same student to lift something much heavier, like your desk or maybe to lift up another student (if you think you can handle the disturbance such a demo will produce in the class). Not so easy lifting heavy weight, is it? That's because the heavier object needed more work. You have to put more energy into it.
Now power. By definition, power is the amount of work done in the unit of tome. 1 Watt = 1 Joule / 1 second. But what does it mean. Put 2 students to make pushups in front of the class. Put them to make 5 push up in a slow peace. Now put them to make another 5 in 2 seconds. Feel the difference? You need more power to make the same work faster. That's power.
That's it about exemplifying and intuitive understanding. They now know Force, Work (Energy) and Power. Mechanics is the only way we can understand, feel something using our intuition.
We have no internal or native representation for electricity, so from now on you'll have to teach electrical force, and the work done by displacing charges by telling them dragging a charge through a field is similar how they have to lift their body while doing pushups.
After you have charges and forces to move them through the electric field, you'll need to define current. Water analogy can be pretty good for a 8th grade student learning electricity. Quantity of water is the charge, molecules of whater can be seen as electrons.
Poke a small whole in the cap of a water bottle and squeeze the water gently, pointed to the class. That's a small current. Now squeeze harder toward them, hard enough to scare them of getting wet, but without the water touching any of them. That was a bigger current, because more water per second passed through that hole in the cap.
For a P = U*I demo would mean a too elaborated analogy. I would just fell back and refer to mechanical power, then use formulas to derive P = U*I
Even if you find a good analogy for P=U*I, not many would get it right. Keep in mind they don't know the expected outcome, so they don't know what to take away from an experiment or from an analogy. Always state what to take away from it right after an experiment, an analogy or an explanation. The conclusion must always be stated crisp and clear, even when the conclusion might seem obvious to you.
Depending on how much materials/labs the school has, at some point would be great to leave water analogy and start experimenting with electricity. PC simulations or visualizations will only please or bore them, but won't teach much. You'll have to make them interact with electricity, you'll have to teach them to predict the outcome then try to very in practice. You'll have to engage them emotionally (though without creating complete chaos in the class). They'll have to engage at least 1-2 more senses to remember, they'll need to touch the wires, make a circuit by themselves, see a lightbulb lighting and feel it's heat at touch, and so on. Just looking at a youtube class won't teach them much.
And whatever you do, don't play a slideshow while explaining. Slides competes for the student's attention with your explanation, only split their attention and make them remember even less.
You can keep the slides on for yourself only, to guide you through the material and to make sure you don't forget to teach the key steps. Again, I'm not a teacher, just telling some parts from some of the teachers I have had, and I can still remember as good ones.
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Outrageous the last 2 definitions, if not dead wrong, but I'm not a physicist.
Also, to me they clarify as much as a marketing blurb, "recognizable in the performance of work" almost shut down my brain and put me to sleep. :-//
Outrageous, maybe. But sometimes you have to live with that, because it is the best that can be said.
The best that can be said about energy is that it is a certain measurable quantity, that by experiment, is conserved. Nobody can isolate energy, nobody can put it in a bottle and say "that's energy". It is an abstract concept, not a material thing.
Energy also has a quality that determines how useful it is. A room full of room temperature air has a certain amount of energy. A small pot of boiling water may have the same amount of energy. But the small pot of boiling water is more useful than the room full of air.
There are many laws that describe how energy behaves, how it can be transformed, and how it can be used, but that is the limit of understanding. To understand energy is to understand how the concept can be applied, not to understand what it is. You can't understand what energy is. You can only understand what it does.
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And whatever you do, don't play a slideshow while explaining. Slides competes for the student's attention with your explanation, only split their attention and make them remember even less.
No, this is nonsense. Have you never heard the phrase "a picture is worth a thousand words"? You put a picture or a diagram on the slide, and then you talk about the slide while the audience is looking at it. Then you can convey information in two ways at the same time: visually and verbally.
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Wikipedia is not exactly the place to look to understand physics stuff. It is however an adequate place to look up a formula for Physics things you already understood but merely forgot the formula.
The better place to look is the websites of Physics Department at any university -- a place where correctness and reputation affects their ability to make a living. For very basic Physics, a traditional (for $) encyclopedia such as Britannica would likely be adequate.
Swimming on the surface: Encyclopædia Britannica
https://www.britannica.com/browse/Matter-Energy (https://www.britannica.com/browse/Matter-Energy)
Diving deep: U of Colorado Physics Department (one example or many)
https://physicscourses.colorado.edu/phys2010/old2010Directories/phys2010_fa10/LectureNotes/EnergyandWork.pdf (https://physicscourses.colorado.edu/phys2010/old2010Directories/phys2010_fa10/LectureNotes/EnergyandWork.pdf)
As U of Colorado Physics Dept's PDF pointed out, most merely use the more abstract definition of Energy as "the ability to do work" or similar. I choose the word "capacity" because I think "capacity to do work" describes it better. "Ability" can be binary: you can or you cannot. Whereas "Capacity" suggests quantification is meaningful.
Don't try to dive too deep. For most fields in Physics, there is a depth where even PhD physicist in that particular field can't yet swim. Many fundamental principals in Physics has yet to be better explored. With our ability to observe the universe improves, more conflicts are being discovered. Problems such as endless Expansion of the Universe while holding onto Conservation of Energy is a rabbit hole. Even how gravity holds the galaxy together is in question - is it dark matter or is it MOD (Modified Gravity) or are they really the same? So on, so on. So swim on the surface and go only as deep as you must.
With that in mind, my suggestion is: use the abstract definition of energy being "ability/capacity to do work", and power is "how much energy you use per unit time." Further, my opinion is: do not start your explanation with a formula -- a formula describes how to quantify (evaluate) it but doesn't explain what it is. Quantification is meaningless without knowing what you are quantifying.
If you need to go slightly deeper:
> Battery stores it power by altering molecular bonds - changing the chemical (molecular) bonds from higher energy ones to lower energy ones thereby releasing some energy to be use.
> Fission Nuclear power plants extract it energy by altering subatomic bonds. Changing Elements by changing higher level energy subatomic bonds to lower energy ones by splitting the atom thereby releasing energy to be use.
> Fusion power plants (the Sun or stars) extract its energy by altering subatomic bonds to lower energy ones. Done by merging atoms into different atoms. Different kind of stars (or a star in different stages) merge different kind of atoms (elements) and creates different atoms. Our Sun is merging Hydrogen now making Helium, someday, we will be merging Helium. Our ability to further understand Physics likely already stopped or will be stopping soon after the Hydrogen ran out.
> Gravity, Potential and Kinetic Energies -- I know the formulas and how to evaluate it. I know some representations of it (such as warping of space, Graviton, or whatever). But I don't know fundamentally what it is.
If you dive deep enough, you would be there alone... Good luck and hope this helps in your quest.
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@IanB Care to explain what on Earth is "performance of work" in physics, please? Never heard of that. We don't have this term (outside of HR maybe - Human Resources department).
The closest term I know related with "performance" and work (W=F*d) in physics would be lowercase Eta \$\eta\$, which we used to use for mechanical randament (efficiency, don't know the correct English term used in physics), I mean the ratio between useful output versus total input. Though, I don't think "performance" word in "performance of work" is about \$\eta\$. Maybe it's some English idiom I don't know. :-//
I never said to not use images at all (so your argument with a picture a thousand words argument is not appropriate here). I said to not play slides in parallel with the teaching. Slides are very bad to keep on in parallel with the teaching, and advance the slides while the lesson goes on. I know this from my own experience, and it's not some personal deficiency. I've asked a few times and it's very common. Unless the speaker is particularly gifted, people will look mostly at the slides.
Slides usually contain a few lines of text, too, besides images and formula. Reading is reflex, one can not look at a text without involuntarily reading it. If the slide stays on all the time, this makes the audience to keep reading those 2-3 lines of text instead of following the thread of thoughts explained by the teacher, or it makes them to keep looking over and over at the same drawing while the explanation had advanced from that drawing minutes ago.
Another reason against slides is that handwritten diagrams and text are retained more easily than perfectly printed material. A draft handmade diagram at the table is preferable to a projection of a diagram drawn in Visio or alike software, with perfectly straight lines.
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The problem is that electrical energy and electrical power are interrelated concepts.
Electrical power can be defined as voltage times current, but that does not explain what it is. It can also be defined more intuitively as the amount of energy consumed per second.
Electrical energy on the other hand is defined as the total work done or the total heat generated, but its formula is power times time.
It seems difficult to explain one concept without the other. They must be explained at the same time, but you have to start somewhere.
I remember that I had a hard time understanding these two concepts at first because they were similar and related.
How would you explain these two concepts to someone who does not know anything about electrical power and energy?
Hello there,
The most basic form of power is instantaneous power. That is power that does not do anything during one instant, which is really zero time.
So for zero time, that is no time passing yet, we still have power and that power can be expressed as a number like 100 and usually in watts.
So if you have 100 watts, you have 100 watts. There is no energy yet. It's only when you allow time to pass that you will see energy.
For example, say you have a 1000 watt light bulb running for 1 hour. The energy is 1000 watt hours. If you have it running for one one-thousandth of an hour (1/1000 of an hour) the energy is 1 watt hour. If you have it running for one one-millionth of an hour, the energy is 0.001 watt hours. If you have it running for one one-billionth of an hour, the energy is 1microwatt. For one one-trillionth of an hour, 1 nanowatt, and for 1000 times less time than that you get 1 picowatt.
If you follow this sequence, if you dont allow any time at all to pass you have 0 watt hours, but the light bulb is still a 1000 watt light bulb.
So the power rating times the time is the energy that would be expended IF the device was allowed to run over that time.
Note that energy is a very real thing, while power is really just a concept. You can have a zillion volts times a zillion amps but if you have no time you have provided for zero energy. The concept of power does allow use to calculate things like energy and to be able to predict what that power may cause, such as energy consumption or lighting effects.
What else is associated closely with power is efficiency. If you have 100 watts in and only 50 watts out, you dont have to calculate energy to know the device is only 50 percent efficient.
Sometimes you can have 100 watts in and 50 watts out but the lighting power is only an equivalent of 20 watts. Since you have 100 watts in and only 20 watts (of lighting power) out, the efficiency is only 20 percent, but then we call it efficacy rather than efficiency.
The main goal is really to understand how to calculate things like energy and power and possibly efficiency and/or efficacy. Once you know that you can consider yourself a person who understands power and energy. You might also start to look into power and energy in transient circuits where the power is not constant over time like the above examples. Sometimes the power can vary a lot over time and then you have to calculate the average power and/or peak power or the energy.
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@IanB Care to explain what on Earth is "performance of work" in physics, please? Never heard of that. We don't have this term (outside of HR maybe - Human Resources department).
No. I checked my posts above and I never used those words.
Regarding presentations, I think that good presentations combine words and images. We all know about "death by PowerPoint", but then again there are whole classes about creating effective presentations.
It is true that people will read slides instead of listening, but then put on the slide what you want people to remember and then they will have a memory aid.
One of the presentation skills is to put up a slide, give the audience time to view and absorb it, and then start speaking. Don't make people divide their attention between your voice and the slide. When you speak, you will expand upon the slide, not simply repeat what it shows. The slide should make people ask questions, like "what is this all about?". And then you will answer those questions. The audience will listen to you because they will want to know what the slide doesn't tell them.
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Never mind with the explanation. Those words were in the definition taken by Picuino from Wikipedia, the definition that made me rant comparing it with marketing blurb that doesn't make any sense:
Wikipedia:
Energy is the quantitative property that is transferred to a body or to a physical system, recognizable in the performance of work and in the form of heat and light.
The law of conservation of energy states that energy can be converted in form, but not created or destroyed.
The unit of measurement for energy in the International System of Units (SI) is the joule (J).
About slides, I think we both got each other's points. You like slides, I don't. :)
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We don't have a well-defined mental image of energy. We debated its existence for over 100 years. We play with it mathematically. It flows from my wife's fingers and into the mechanical mechanism of our grandfather clock; where it is mechanically stored in heavy masses. Perhaps someday.............
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As U of Colorado Physics Dept's PDF pointed out, most merely use the more abstract definition of Energy as "the ability to do work" or similar. I choose the word "capacity" because I think "capacity to do work" describes it better. "Ability" can be binary: you can or you cannot. Whereas "Capacity" suggests quantification is meaningful.
We manage to make it abstract in time, but at first it was dead simple: the work to pump the water out of the coal mine. ;D
Not joking, it's from a history of science book: During the 18'th century in England, there were a lot of coal mines, and they needed to pump out the water. That was the "work", pumping out the water, and that's why the term "work" in physics.
At some point, they invented a steam-pump, and everybody was talking about turning heat into work, so pumping out the water using heat. That's why "work" in physics, by definition is W=F*d. F was the force to move the piston, and d the displacement of the piston. Everybody was using the term work, including Carnot and Joule. Joule realized that "heat" and "work" were convertible from one to another in either direction. He made experiments and measurement, and noticed that nothing is lost during the conversions from heat to work or from work to heat.
Later, Lord Kelvin preferred the term "energy" in order to unify the concepts of "heat" and "work", and because of the Jule's measurements, the idea of conservation of energy was introduced. Then, the "energy" concept was extended to other forms than "work" and "heat".
In Greek, "energy" means "the work within".
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At some point, they invented a steam-pump, and everybody was talking about turning heat into work, so pumping out the water using heat. That's why "work" in physics, by definition is W=F*d. F was the force to move the piston, and d the displacement of the piston. Everybody was using the term work, including Carnot and Joule. Joule realized that "heat" and "work" were convertible from one to another in either direction. He made experiments and measurement, and noticed that nothing is lost during the conversions from heat to work or from work to heat.
Later, Lord Kelvin preferred the term "energy" in order to unify the concepts of "heat" and "work", and because of the Jule's measurements, the idea of conservation of energy was introduced. Then, the "energy" concept was extended to other forms than "work" and "heat".
This is not accurate thermodynamics.
Work and Heat are the only two forms of energy in thermodynamics. Work can be converted to Heat without loss, but the converse is not true. You cannot convert Heat to Work with 100% efficiency. That is why all heat engines produce waste heat.
Thermodynamics has a rigorous mathematical framework that joins everything together. It is very difficult to discuss thermodynamic concepts in detail without resorting to mathematics and the careful and precise use of the associated quantities like temperature, energy, work, heat, entropy, free energy and so on.
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I should have phrased that more careful. "No loses" as in "energy is always conserved" not as in "efficiency". That's how the energy conservation idea started, Joule observed no losses during conversions from one to another (as in no heat or work were disappearing).
That's why I wrote "and because of the Jule's measurements, the idea of conservation of energy was introduced".
Anyway, the whole tale is the pitch for "energia word was chosen to denote the work within". I've just checked what Google knows about the Greek word energy, and it seems close enough with the tale I remember from that audiobook:
From Google search:
Noun. ἐνέργειᾰ • (enérgeia) f (genitive ἐνεργείᾱς); first declension. activity, operation, vigour. workmanship.
ἐνέργεια - Wiktionary
en.wiktionary.org › wiki › ἐνέργεια
The word “energy” comes from the Greek enérgeia. Developed by Aristotle, enérgeia has no direct translation to English. It is frequently described as “being at work”.
The History of the Word "Energy"
home.uni-leipzig.de › energy › energy-fundamentals
That tale from that book and the takeaway from it: energy in Greek means the work within has come to mind only after I've read the term preferred by Rick Law: "capacity to do work" (instead of ability to do work), and that's why I was quoting him before telling the tale.
The book I am referring is "The History of Science" by Peter Whitfield. A beautiful book, an absolute delight to listen to. I didn't notice any mistakes, though the author is self-published.
https://www.amazon.com/History-Science-Peter-Whitfield-ebook/dp/B008PX0VYY (https://www.amazon.com/History-Science-Peter-Whitfield-ebook/dp/B008PX0VYY)
https://www.amazon.com/History-Science-Peter-Whitfield/dp/962634993X (https://www.amazon.com/History-Science-Peter-Whitfield/dp/962634993X)
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The flow of heat energy is governed by a few extra thermodynamic laws and may be confusing to novices.
I find the concepst of energy and power as described in my first reply dealing with mechanical energy to be readily understandable since we all lift things, and feel the forces with our nervous system.
To improve the discussion of mechanical power, one can point out that a weak power source will take longer to accomplish the same lift as a stronger power source that can apply the same energy in a shorter time.
The classical "simple machines" (lever, pulley, inclined plane, screw, etc.) can be added to the discussion to see how the same amount of energy can be used in different applications.
Thereafter, the lecture can proceed to the other forms of energy, conversion, conservation, etc.
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You need to simplify and reduce irrelevant details. If you want to explain electrical energy and power, you don't have to talk about voltages and currents at all. They are lower-level details.
You need to get to the key point.
People intuitively understand what energy is. They understand if they eat too much energy, they gain weight. They are billed for electrical energy. They understand that to drive 100km, you need 7 liters of gasoline which has xxx amount of energy. Or you spent that or that much energy during a year.
Joule is the unit of energy. Everybody knows that, from food things.
Then the rest is easy: power is just SPEED. It's the rate of energy transfer. Unit of power is JOULES PER SECOND. Just like unit of travel speed is kilometers/miles per hour. This is highly intuitive (opposite, something times something, like watt-hours, are not).
Forget everything else. That's it. You can mention Watt is just a synonym, alternative name for "joules per second".
When you need to start explaining the backwards definition where speed is the primary unit and energy is a multiplication of two primary units, you have lost half of your audience. You need serious mathematical understanding for that - even if it's something taught in primary school, in theory.
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A key point to accept is that in Physics (or EE for that matter), the deeper you dive, the more complex that situation. We (human beings) observed the phenomenon and derived terms to describe them far before we acquire adequate understanding of them. So we get to messy situations like electron flow vs current flow.
That isn't even an ancient vs modern situation. My favorite example is "calorie vs Calorie." Physics came up with the definition of calorie in the early 1800's, but someone must have read something wrong. Calorie first used by nutritionist was done wrong, possibly added a "k" (as in 1 kg) or missed an "m" (as in 1 ml). So now we use Calorie for food/nutritionist related, and calorie for Physics related. 1 Calorie in food is 1000 calorie in Physics.
We have to accept and live with the confusion. Current will flow in opposite direction as electrons flow, Physicist will eat 1000x the calories labeled on the ice-cream container, and the words to describe phenomenon(s) can be wrong or misleading. That's life, accept it. That acceptance should also include mathematics. Mathematics merely describes the world we perceive and allows us to quantify or to predict. Nature may actually be entirely different and what we know is merely a mathematical approximation that seem to work... Case and point, Newtonian vs Relativity vs whatever to come in the future. Relativity doesn't work with Quantum Mechanics, and Quantum Mechanics (wave equation) doesn't have Time. So is Time and Space even real?
In the time I wrote this reply, another few hundred tons of Hydrogen got burnt up by the Sun. We now have less time left to gain that understanding... Point proven, I think - I believe we all understood the immediate prior statement without diving into what Time really is in nature and how much the Sun consumes per second, sun spots, and how consumption may change as solar mass change...
Thus my suggestion: Don't dive too deep, you can spend days trying to explain what is a "point" (in math vs in reality) and get no where. Take your audience only as deep as you must to understand "energy v power" and don't be afraid of saying "we don't know" because we really don't know.
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Our minds trick us into thinking that the name of a thing and the thing are the same.
Words an only be explained using other words.
It gives rise to the illusion that the universe is made up of separate parts.
It isn't.
There are only localised qualities drifting about. That's all.
Dont worry.
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However, we can use the standard concepts of physics to calculate accurately many useful quantities.
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A key point to accept is that in Physics (or EE for that matter), the deeper you dive, the more complex that situation. We (human beings) observed the phenomenon and derived terms to describe them far before we acquire adequate understanding of them. So we get to messy situations like electron flow vs current flow.
That isn't even an ancient vs modern situation. My favorite example is "calorie vs Calorie." Physics came up with the definition of calorie in the early 1800's, but someone must have read something wrong. Calorie first used by nutritionist was done wrong, possibly added a "k" (as in 1 kg) or missed an "m" (as in 1 ml). So now we use Calorie for food/nutritionist related, and calorie for Physics related. 1 Calorie in food is 1000 calorie in Physics.
We have to accept and live with the confusion. Current will flow in opposite direction as electrons flow, Physicist will eat 1000x the calories labeled on the ice-cream container, and the words to describe phenomenon(s) can be wrong or misleading. That's life, accept it. That acceptance should also include mathematics. Mathematics merely describes the world we perceive and allows us to quantify or to predict. Nature may actually be entirely different and what we know is merely a mathematical approximation that seem to work... Case and point, Newtonian vs Relativity vs whatever to come in the future. Relativity doesn't work with Quantum Mechanics, and Quantum Mechanics (wave equation) doesn't have Time. So is Time and Space even real?
In the time I wrote this reply, another few hundred tons of Hydrogen got burnt up by the Sun. We now have less time left to gain that understanding... Point proven, I think - I believe we all understood the immediate prior statement without diving into what Time really is in nature and how much the Sun consumes per second, sun spots, and how consumption may change as solar mass change...
Thus my suggestion: Don't dive too deep, you can spend days trying to explain what is a "point" (in math vs in reality) and get no where. Take your audience only as deep as you must to understand "energy v power" and don't be afraid of saying "we don't know" because we really don't know.
Historically, the "calorie" was used by chemists and others working with liquids.
The modern definition of calorie is the heat required to raise 1 g (very close to 1 cm3) of water by 1 K.
(There was temporary confusion between 1 cm3 and 1 ml, but are now redefined as equal.)
A related definition is the kcal: the hear required to raise 1 kg of water (1000 ml) by 1 K.
In wet chemistry, it is common to measure the energy of chemical reactions by measuring temperature change in liquids with a thermometer.
Somehow, the latter name (often called the "kilogram-calorie") got used by nutritionists and called the "calorie" for simplicity and to confuse real scientists.
It was an important discovery to relate the amount of heat energy to mechanical energy .
Benjamin Thompson, Count Rumford did early experiments with temperature rise of cooling water in a cannon-boring lathe, around the turn of the 19th Century.
In the mid-19th century, James Joule estimated from Rumford's results that 1034 ft-lb of energy was equivalent to 1 BTU (heat required to heat 1 lb of water by 1o F).
Joule used this to develop his theory of energy conservation.
Joule was British, and used conventional units.
(The current value is about 778 ft-lb/BTU).
The SI metric unit of energy is named after Joule.
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A key point to accept is that in Physics (or EE for that matter), the deeper you dive, the more complex that situation. We (human beings) observed the phenomenon and derived terms to describe them far before we acquire adequate understanding of them. So we get to messy situations like electron flow vs current flow.
That isn't even an ancient vs modern situation. My favorite example is "calorie vs Calorie." Physics came up with the definition of calorie in the early 1800's, but someone must have read something wrong. Calorie first used by nutritionist was done wrong, possibly added a "k" (as in 1 kg) or missed an "m" (as in 1 ml). So now we use Calorie for food/nutritionist related, and calorie for Physics related. 1 Calorie in food is 1000 calorie in Physics.
We have to accept and live with the confusion. Current will flow in opposite direction as electrons flow, Physicist will eat 1000x the calories labeled on the ice-cream container, and the words to describe phenomenon(s) can be wrong or misleading. That's life, accept it. That acceptance should also include mathematics. Mathematics merely describes the world we perceive and allows us to quantify or to predict. Nature may actually be entirely different and what we know is merely a mathematical approximation that seem to work... Case and point, Newtonian vs Relativity vs whatever to come in the future. Relativity doesn't work with Quantum Mechanics, and Quantum Mechanics (wave equation) doesn't have Time. So is Time and Space even real?
In the time I wrote this reply, another few hundred tons of Hydrogen got burnt up by the Sun. We now have less time left to gain that understanding... Point proven, I think - I believe we all understood the immediate prior statement without diving into what Time really is in nature and how much the Sun consumes per second, sun spots, and how consumption may change as solar mass change...
Thus my suggestion: Don't dive too deep, you can spend days trying to explain what is a "point" (in math vs in reality) and get no where. Take your audience only as deep as you must to understand "energy v power" and don't be afraid of saying "we don't know" because we really don't know.
Hi,
What do you mean by "wave equation doesn't have time" ? You'll have to explain your context.
It's interesting what we call real though. It's almost like current and voltage, by themselves alone, are not real because they cant do anything real by themselves. It takes both to actually cause anything. Although they can influence each other they dont seem to be able to influence anything by themselves alone. A voltage can not do anything unless we allow some current to flow, and a current can not do anything unless we allow some sort of voltage drop. An example for voltage is an ideal capacitor, and for current an ideal inductor short-circuited or a superconductor circuit that forms a continuous loop with no other components in it.
I think we take for granted that they are both real even by themselves, which we do with a lot of things.
I always like to fall back on the "hole in the ground" analogy in philosophy. Is a hole in the ground real? Arguments on both sides, real or not real. A hole is a void not an object in itself, yet we use that void as if it was a physical object.
This gets both interesting and kind of strange and can be confusing.
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Somehow, the latter name (often called the "kilogram-calorie") got used by nutritionists and called the "calorie" for simplicity and to confuse real scientists.
...
Had nutritionist asked a Physicist's input on on correcting the confusion, as they should since a Physicist first coined the term... The Physicist would likely have suggested "call it kalorie". So 1 kalorie equal 1k calorie. Saying "kalorie-with-a-k" causes less confusion than "calorie with a capital C".
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What do you mean by "wave equation doesn't have time" ? You'll have to explain your context.
...
Case and point of diving deep may get yourself caught up in a mess...
Since the topic was about expression of Energy, I was thinking of "Time Independent Schrodinger Equation" (for 1 dimention) which is useful in Energy evaluation. This equation is not related to my immediate prior sentence that "Relativity doesn't work with Quantum Mechanics". They indeed don't work together, but unrelated to the next thought. The next thought is just my own thought process at work -- I went back to energy and my own question about what exactly is space and time.
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...
Somehow, the latter name (often called the "kilogram-calorie") got used by nutritionists and called the "calorie" for simplicity and to confuse real scientists.
...
Had nutritionist asked a Physicist's input on on correcting the confusion, as they should since a Physicist first coined the term... The Physicist would likely have suggested "call it kalorie". So 1 kalorie equal 1k calorie. Saying "kalorie-with-a-k" causes less confusion than "calorie with a capital C".
...
What do you mean by "wave equation doesn't have time" ? You'll have to explain your context.
...
Case and point of diving deep may get yourself caught up in a mess...
Since the topic was about expression of Energy, I was thinking of "Time Independent Schrodinger Equation" (for 1 dimention) which is useful in Energy evaluation. This equation is not related to my immediate prior sentence that "Relativity doesn't work with Quantum Mechanics". They indeed don't work together, but unrelated to the next thought. The next thought is just my own thought process at work -- I went back to energy and my own question about what exactly is space and time.
Ha ha, and nothing may be stranger than a "candle". Who's candle? Kind of funny.
Goes all the way back to a "foot" and how about a "cubit".
Question is, will modern man in the year 4000ad mock our units of today ... "They didn't even understand what quantum entanglement was back then ha ha ha".
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I'd say that continuing problem is naming.
Spoken language has injected time even when it's not obvious.
I'd start from force/power/work and pushing a cart.
Cart is very practical since up and down hills are already known features.
Also including concepts of moment and potential early on.
It's just some trigonometry in practice.
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...
Somehow, the latter name (often called the "kilogram-calorie") got used by nutritionists and called the "calorie" for simplicity and to confuse real scientists.
...
Had nutritionist asked a Physicist's input on on correcting the confusion, as they should since a Physicist first coined the term... The Physicist would likely have suggested "call it kalorie". So 1 kalorie equal 1k calorie. Saying "kalorie-with-a-k" causes less confusion than "calorie with a capital C".
...
What do you mean by "wave equation doesn't have time" ? You'll have to explain your context.
...
Case and point of diving deep may get yourself caught up in a mess...
Since the topic was about expression of Energy, I was thinking of "Time Independent Schrodinger Equation" (for 1 dimention) which is useful in Energy evaluation. This equation is not related to my immediate prior sentence that "Relativity doesn't work with Quantum Mechanics". They indeed don't work together, but unrelated to the next thought. The next thought is just my own thought process at work -- I went back to energy and my own question about what exactly is space and time.
Ha ha, and nothing may be stranger than a "candle". Who's candle? Kind of funny.
Goes all the way back to a "foot" and how about a "cubit".
Question is, will modern man in the year 4000ad mock our units of today ... "They didn't even understand what quantum entanglement was back then ha ha ha".
The "candle" is a "standard candle", originally defined as a one-sixth-pound candle of sperm wax, burning at the rate of 120 grains per hour.
Later definitions used incandescent sources, backwards compatible with that candle.
The modern SI term is the "candela", again backwards compatible, based on a black-body made from tungsten.
Feet and cubits are well-defined for a particular human, as is the spelling of "whose".
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I'd say that continuing problem is naming.
Spoken language has injected time even when it's not obvious.
I'd start from force/power/work and pushing a cart.
Cart is very practical since up and down hills are already known features.
Also including concepts of moment and potential early on.
It's just some trigonometry in practice.
Naming is merely a cultural and language issue. It can be fix if the will to fix it exists. Mile and kilometer are still an expression of length. It will "feel" the same to the "user" which is us mere humans.
Diving into Physics, some equivalences are more problematic. Energy and Mass are equivalent. You can translate from one to the other by a mere constant factor -- exactly like mile and kilometer. But they sure don't "feel" the same to average humans.
So, you are telling me that "this glass of cold water" is equal to gold by merely adding some coal to make it as heavy as gold? Yeah, because they are all just Energy. Well, nature at some level sees it the same; yet at another level, chemical reaction for example, nature sees it very different. (That actually implies properties of observer matters, rather like the duality of particle and wave.)
Abstraction tests the human mind. At times we may not grasp it, then we merely accept it while we explore it more. We accept until we gain more understanding of the fundamentals, it may help but it may not and if so we push for more understanding. There are a lot of fundamentals we are yet missing. Our pace of understanding appeared to have slowed, perhaps because we got most of the low hanging fruits so problems are getting harder. Perhaps we just prefer to spend our resources elsewhere hence we are not pushing forward as hard.
I do hope more kids will go into Physics. We may yet fully understand nature before we (humans) are history.
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...
Somehow, the latter name (often called the "kilogram-calorie") got used by nutritionists and called the "calorie" for simplicity and to confuse real scientists.
...
Had nutritionist asked a Physicist's input on on correcting the confusion, as they should since a Physicist first coined the term... The Physicist would likely have suggested "call it kalorie". So 1 kalorie equal 1k calorie. Saying "kalorie-with-a-k" causes less confusion than "calorie with a capital C".
...
What do you mean by "wave equation doesn't have time" ? You'll have to explain your context.
...
Case and point of diving deep may get yourself caught up in a mess...
Since the topic was about expression of Energy, I was thinking of "Time Independent Schrodinger Equation" (for 1 dimention) which is useful in Energy evaluation. This equation is not related to my immediate prior sentence that "Relativity doesn't work with Quantum Mechanics". They indeed don't work together, but unrelated to the next thought. The next thought is just my own thought process at work -- I went back to energy and my own question about what exactly is space and time.
Ha ha, and nothing may be stranger than a "candle". Who's candle? Kind of funny.
Goes all the way back to a "foot" and how about a "cubit".
Question is, will modern man in the year 4000ad mock our units of today ... "They didn't even understand what quantum entanglement was back then ha ha ha".
The "candle" is a "standard candle", originally defined as a one-sixth-pound candle of sperm wax, burning at the rate of 120 grains per hour.
Later definitions used incandescent sources, backwards compatible with that candle.
The modern SI term is the "candela", again backwards compatible, based on a black-body made from tungsten.
Feet and cubits are well-defined for a particular human, as is the spelling of "whose".
Modern definitions attempt to refine, I was reflecting on original history. In particular, look at the biblical definition of cubit.
We can guess where candle and foot started from. Also check out inch and fathom.
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Yes, the inch originated as three barleycorns.
Architects in biblical times used cubits.
My "span" (thumb to little finger when laid flat) is very close to exactly 9 in: wherefore I can say that I have nine inches, but don't use it as a rule.
However, it is handy in measuring length of coax cable.
The fathom and yard originated with sailors and tailors (respectively) measuring rope and cloth with their hands.
When a novice student is introduced to science, it is important to emphasize technical usage and definitions of words (such as force) with which he is already familiar in non-technical contexts.
The first stumbling block for a new physics student is often the distinction between "mass" and "weight".
When such terms are confused, it is harder to understand the physical equations that relate them in technical use.
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You need to simplify and reduce irrelevant details. If you want to explain electrical energy and power, you don't have to talk about voltages and currents at all. They are lower-level details.
You need to get to the key point.
People intuitively understand what energy is. They understand if they eat too much energy, they gain weight. They are billed for electrical energy. They understand that to drive 100km, you need 7 liters of gasoline which has xxx amount of energy. Or you spent that or that much energy during a year.
Joule is the unit of energy. Everybody knows that, from food things.
Then the rest is easy: power is just SPEED. It's the rate of energy transfer. Unit of power is JOULES PER SECOND. Just like unit of travel speed is kilometers/miles per hour. This is highly intuitive (opposite, something times something, like watt-hours, are not).
Forget everything else. That's it. You can mention Watt is just a synonym, alternative name for "joules per second".
When you need to start explaining the backwards definition where speed is the primary unit and energy is a multiplication of two primary units, you have lost half of your audience. You need serious mathematical understanding for that - even if it's something taught in primary school, in theory.
That's what I'm going to do. I'm not going to try to define energy with just one sentence.
Instead, I'm going to describe its different forms (potential energy, radiant energy, thermal energy, etc.) and its different primary sources (oil, natural gas, nuclear, wind, solar, tidal, geothermal, etc.).
After this introduction, I will describe the particular characteristics of electrical energy and finally its formula (E=P·t) and some practical exercises to help students understand how the power and operating time of an appliance affects the electric bill.
Edit: The problem of how to account for electrical power remains the same. I don't know whether to explain it earlier or later. I think it is best to explain it after energy, once they have seen the importance of knowing power to calculate energy.
In any case I will try to make it as simple and practical as possible.
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I disagree that people's intuitive understanding of "energy" is a good starting point.
My preference for a good starting point is their understanding of "force", from which one derives the concept of work/energy.
If you use some elementary machines at that point in the lecture, such as a lever, you can see how a short travel of a higher force equals a long travel of a lower force, for the same work/energy.
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That's what I'm going to do. I'm not going to try to define energy with just one sentence.
Instead, I'm going to describe its different forms (potential energy, radiant energy, thermal energy, etc.) and its different primary sources (oil, natural gas, nuclear, wind, solar, tidal, geothermal, etc.).
...
In any case I will try to make it as simple and practical as possible.
I don't know if Spain has it too... In the USA, emergency gas powered electric generator is rather common. A page from their advertisement / website could be a good "teaching tool" for you. You have an example at hand of electricity generation. Probably (if advertisement is like here) advertisements/website have info on Wattage (max power), gas consumption (how long can a gallon of gas last running this 1KW generator, which of course would depend on how many Watt's you are consuming). Etc. Etc.
As intro to discussing alternate generation source, talk cars. Horse-power (or whatever car advertisements use in Spain) to describe car engine's max power, Miles per gallon (km per litre) describes cumulative energy used to do work (of moving at X miles at speed of whatever). Besides using engine to move the car, there is an electrical generator there too, so immediate alternate source for electrical generation - car engine! So on, so on. I am sure you can think of other potentially helpful use for this "teaching tool."
Now if you have some info on how many Watt your LCD TV use, (same for refrigerator, vacuum clean... ). Actual example(s) for home item consuming energy, you can even show some example of how many WH did you consume just watching the movie "Top Gun" or whatever is popular in Spain in moment.
By the time you are done with those examples, switching the thought to alternate source (and their associated cost/efficiency) such as Wind, Solar, Hydro should be effortless, in my opinion.
Hey, good luck and hope it goes well for you. Tell us how it went after, many here likely would like to know.
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Yes, the inch originated as three barleycorns.
Architects in biblical times used cubits.
My "span" (thumb to little finger when laid flat) is very close to exactly 9 in: wherefore I can say that I have nine inches, but don't use it as a rule.
However, it is handy in measuring length of coax cable.
The fathom and yard originated with sailors and tailors (respectively) measuring rope and cloth with their hands.
When a novice student is introduced to science, it is important to emphasize technical usage and definitions of words (such as force) with which he is already familiar in non-technical contexts.
The first stumbling block for a new physics student is often the distinction between "mass" and "weight".
When such terms are confused, it is harder to understand the physical equations that relate them in technical use.
Yes i was asked one time: "How much does the Earth weigh".
Then also: "Wait until we set the clocks ahead one hour, you will get more sun".
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Yes, the inch originated as three barleycorns.
Architects in biblical times used cubits.
My "span" (thumb to little finger when laid flat) is very close to exactly 9 in: wherefore I can say that I have nine inches, but don't use it as a rule.
However, it is handy in measuring length of coax cable.
The fathom and yard originated with sailors and tailors (respectively) measuring rope and cloth with their hands.
When a novice student is introduced to science, it is important to emphasize technical usage and definitions of words (such as force) with which he is already familiar in non-technical contexts.
The first stumbling block for a new physics student is often the distinction between "mass" and "weight".
When such terms are confused, it is harder to understand the physical equations that relate them in technical use.
Yes i was asked one time: "How much does the Earth weigh".
Then also: "Wait until we set the clocks ahead one hour, you will get more sun".
Henry Cavendish "weighed the Earth" in 1798 by measuring the gravitational constant G, comparing it with the local gravitational acceleration g and the radius of the Earth, to obtain its mass.
An intelligent question: it leads into a pedagogical discussion of the relationship between gravitational mass, inertial mass, and weight.
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Yes, the inch originated as three barleycorns.
Architects in biblical times used cubits.
My "span" (thumb to little finger when laid flat) is very close to exactly 9 in: wherefore I can say that I have nine inches, but don't use it as a rule.
However, it is handy in measuring length of coax cable.
The fathom and yard originated with sailors and tailors (respectively) measuring rope and cloth with their hands.
When a novice student is introduced to science, it is important to emphasize technical usage and definitions of words (such as force) with which he is already familiar in non-technical contexts.
The first stumbling block for a new physics student is often the distinction between "mass" and "weight".
When such terms are confused, it is harder to understand the physical equations that relate them in technical use.
Yes i was asked one time: "How much does the Earth weigh".
Then also: "Wait until we set the clocks ahead one hour, you will get more sun".
Henry Cavendish "weighed the Earth" in 1798 by measuring the gravitational constant G, comparing it with the local gravitational acceleration g and the radius of the Earth, to obtain its mass.
An intelligent question: it leads into a pedagogical discussion of the relationship between gravitational mass, inertial mass, and weight.
Well a question is where are you weighing it. Weight of the Earth on the Earth doesn't make any practical sense, and weighing it on the moon neither, maybe weighing it on the Sun if it and the scale doesn't melt first :-).
If you could accept that somehow it could be done practically, then the weight varies depending on where you measure it.
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That's what I said: Cavendish measured the Earth's mass centuries ago.
This discussion is about how to teach novice students about energy, power, etc.
Prior to a useful discussion thereof, the student needs to understand the difference between mass and weight.
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Normal coordinate system.
Draw a rectangle, V * I, turn Z-axle from back to the right, draw a box, W * s.
Newton is not working, nor is Watt.
How do you visualize kgm2/s2, I can't.
On the other hand, torque is pretty clear.
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Hey, good luck and hope it goes well for you. Tell us how it went after, many here likely would like to know.
This is how the automatic translation into English has turned out for now. I still need to add the explanation of some calculation exercises, translate also the exercises and correct the translation to consider it finished.
https://www.picuino.com/en/electric-energia.html (https://www.picuino.com/en/electric-energia.html) (English version)
Thank you all for your help.
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Some suggestion for improvement here if you like:
(1)
You have "Potential mechanical energy" and "Kinetic mechanical energy" -- both are miss-titled, you need to get rid of the word mechanical in both cases.
Mechanical energy is something like a rubber band or spring. It stores the energy in a mechanical manner. A Spring need not move or does it need gravity to pull something in or push something away. Flywheel is a bit different, that one is kinetic (in the way it stores energy only, input and output are mechanical, typically).
(2)
Potential Energy is due to position relative to another body (note the word gravity is not present). You can have electrical potential energy such as anything electrically-negative charged attracts something electrically-positive charged. No gravity involved, but electrical or magnetic attractive forces are zillion (and zillion and zillion...) times stronger that gravitational attraction force. Example could be static electric in the winder, rubbing a plastic ruler could attract tiny bits of paper demonstrating the attraction force. Van de Graaff Generator on the other hand just continuously build up the electrical charge (on the ball) and the Potential Energy of the electrical charge (on the ball) is used directly rather like the static electricity discharge shock one can get in the winter.
Your example of the dam, while it uses potential energy - actually use kinetic energy in the final step to spin the generator. The falling water moves (fall=motion) and the moving water spins a wheel of a dynamo/generator of some sort to convert that water flow.
(3)
Your kinetic energy example is windmill. The only difference between the dam and the windmill is water vs air. One use water motion to spin the generator, the other one use air motion to spin the generator. A flywheel is probably a better example of use of kinetic energy. One can store (water behind the dam), the other one cannot store. You may need to rethink this.
(4)
Almost all power generation may involve multiple conversion. Your example of Chemical Energy of burning fuel producing (convert it to) thermo energy is right, but that is only if you are consuming the heat such as in heating the house. Electricity generation via natural gas or oil may use thermo to convert water to steam. Diesel can also be use but in this case is using fossil fuel to drive a engine (spinning the shaft via gas explosion). The mechanical energy of the spin (like water from dam) spins the wheels of the electrical generator to get electricity.
On the other hand, electricity generation by nuclear fuel use nuclear fission also create thermo energy (via a thermo transfer liquid) to heat up water to steam. The expansion of water to steam spins the wheels of the electrical generator. So, a nuclear sub or nuclear carrier are really steam ships. The only difference here is nuclear use atom splitting for heat instead of burning oil/natural gas for heat.
So, you should consider this "multiple conversion" and integrate into your descriptions between each type.
(5)
For sure, you need to say "here are some of the examples, there are many other forms of energy we left out since they are less common in electricity generation." Something like that to cover other energies you don't want to discuss.
(6)
Lastly, spinning a generator is almost always the final step in typical electrical generation. So I think each type "potential, whatever" should clearly say that they are just the first step. They all get converted, some multiple times, into the spinning of the shaft of the generator, typically anyhow.
Sorry, a bit rushed since I am delaying dinner. I hope what I wrote here are helpful and please excuse typos.
-
Normal coordinate system.
Draw a rectangle, V * I, turn Z-axle from back to the right, draw a box, W * s.
Newton is not working, nor is Watt.
How do you visualize kgm2/s2, I can't.
On the other hand, torque is pretty clear.
Hi,
Sometimes you can 'step' the variables and do the math. Instead of 0 to 10 and all fractions in between, do just the integers 1,2,3,etc which gives you just 10 results to look at. You can even reduce that to 2,4,6,8,10 and look at just 5 results to see if it makes sense.
When you do it that way it may be a rough approximation but still lets you get a good idea what is happening.
-
Some suggestion for improvement here if you like:
Thank you very much, I really appreciate all the suggestions.
1) Changed
2) I don't quite understand what I should change here, but I have better described the process of energy conversion in a dam.
3) I believe that the energy stored in a dam is potential energy, while the energy stored by the wind is kinetic energy. Then comes the harnessing which is achieved by various intermediate conversions with other forms of energy.
4) I have included an explanation of energy conversion in several steps.
5) I have added mechanical energy and a note that these are the most common forms of energy. What other forms of energy are there?
6) I think this is clarified in the new section on energy form transformations.
https://www.picuino.com/en/electric-energia.html (https://www.picuino.com/en/electric-energia.html)
Best regards.
-
Hey, good job! I have round 2 of suggestions below. But we are down to "refinements" instead of "corrections" already.
--------------------------------------
"Potential energy -
It is the energy that an object has due to its position in a gravitational field."
A clarification before the statement may be helpful. "While there are other forms of potential energy, but in the context of electric generation we will typically be referring to Potential Energy in a gravitational field..."
--------------------------------------
"Kinetic energy
It is the energy that an object has due to its speed of movement."
The words "speed of movement" could be replaced with just "motion". A statement such as "It is the energy of an object due to its motion. The faster the motion, the more the energy. Mathematically, the kinetic energy is proportional to "the Square of the Velocity".
--------------------------------------
"Thermal energy
... ...
This is the most degraded form of energy and it is the most difficult to transform, especially if it is at low temperatures."
This statement bugs me since "degraded form" is not well defined. Bugs me, but I think I understand what you are saying. It may be adequate but can easily lead to wrong interpretation. You can eliminate that statement without affect the content of that paragraph. An alternate way to saying what I think you want to express may be: "Typically, wasted energy eventually dissipate as heat without performing useful work."
--------------------------------------
"Chemical energy
....
To release this energy it is necessary to cause chemical reactions, which in most cases consist of burning fuels with oxygen."
While using the word "burning" can be technically correct, but "burning" suggest fire and flame to most audience. There is no flame they can see when their ATP molecules are oxidized. Thus, I suggest replacing "...burning fuels with oxygen..." with "...the fuel reacts with oxygen releasing energy in the process..."
--------------------------------------
"Electric energy
...A disadvantage of electrical energy is that it cannot be easily stored, it must be consumed at the moment it is created. In order to store electrical energy, it is necessary to convert it into chemical energy in batteries or into mechanical energy in pumped hydroelectric plants."
Your statement is entirely correct. But from prior paragraphs, your target audience is not likely to know what is "pumped hydro storage". You may expand that with an added line "Pumped Hydro is essentially excess energy from solar or wind farms are used to pump water back above a dam to store, and when needed re-convert it back to electrical energy like any other dam"
--------------------------------------
Speaking of dams, I am thinking you may want to point this out as well:
There are risks with dams too, regular dam -- pump or no pump. Earthquake due to a dam is not unusual. After all, you are adding a lot of weight to that little area behind the dam.
Take a look at this article and decide for yourself if you want to add a word or two about that.
https://archive.internationalrivers.org/earthquakes-triggered-by-dams
Windmill kills birds, solar farm has its own drawback, nature doesn't give us anything for free I suppose.
--------------------------------------
Hey, good job there! We can refine till kingdom comes, but even if you don't include any of these round 2 improvements, there isn't much one can complain about.
-
"Thermal energy
... ...
This is the most degraded form of energy and it is the most difficult to transform, especially if it is at low temperatures."
This statement bugs me since "degraded form" is not well defined. Bugs me, but I think I understand what you are saying. It may be adequate but can easily lead to wrong interpretation. You can eliminate that statement without affect the content of that paragraph. An alternate way to saying what I think you want to express may be: "Typically, wasted energy eventually dissipate as heat without performing useful work."
I think "degraded form" is somewhat well defined especially in engineering and thermodynamics.
First of all, heat is the eventual destination of all other forms of energy, and it is something of a one-way trip. Once energy is dissipated as heat, it is not possible to get all of it back again. Some of it is lost forever.
Secondly, it is common in engineering to talk of "low grade heat", which is heat at a low temperature. The lower the temperature, the less the usefulness of the energy content. This somewhat corresponds to higher entropy, but it is not appropriate to introduce entropy at this level of discourse.
-
Hey, good job! I have round 2 of suggestions below. But we are down to "refinements" instead of "corrections" already.
--------------------------------------
"Potential energy -
It is the energy that an object has due to its position in a gravitational field."
A clarification before the statement may be helpful. "While there are other forms of potential energy, but in the context of electric generation we will typically be referring to Potential Energy in a gravitational field..."
--------------------------------------
"Kinetic energy
It is the energy that an object has due to its speed of movement."
The words "speed of movement" could be replaced with just "motion". A statement such as "It is the energy of an object due to its motion. The faster the motion, the more the energy. Mathematically, the kinetic energy is proportional to "the Square of the Velocity".
--------------------------------------
"Thermal energy
... ...
This is the most degraded form of energy and it is the most difficult to transform, especially if it is at low temperatures."
This statement bugs me since "degraded form" is not well defined. Bugs me, but I think I understand what you are saying. It may be adequate but can easily lead to wrong interpretation. You can eliminate that statement without affect the content of that paragraph. An alternate way to saying what I think you want to express may be: "Typically, wasted energy eventually dissipate as heat without performing useful work."
--------------------------------------
"Chemical energy
....
To release this energy it is necessary to cause chemical reactions, which in most cases consist of burning fuels with oxygen."
While using the word "burning" can be technically correct, but "burning" suggest fire and flame to most audience. There is no flame they can see when their ATP molecules are oxidized. Thus, I suggest replacing "...burning fuels with oxygen..." with "...the fuel reacts with oxygen releasing energy in the process..."
--------------------------------------
"Electric energy
...A disadvantage of electrical energy is that it cannot be easily stored, it must be consumed at the moment it is created. In order to store electrical energy, it is necessary to convert it into chemical energy in batteries or into mechanical energy in pumped hydroelectric plants."
Your statement is entirely correct. But from prior paragraphs, your target audience is not likely to know what is "pumped hydro storage". You may expand that with an added line "Pumped Hydro is essentially excess energy from solar or wind farms are used to pump water back above a dam to store, and when needed re-convert it back to electrical energy like any other dam"
--------------------------------------
Speaking of dams, I am thinking you may want to point this out as well:
There are risks with dams too, regular dam -- pump or no pump. Earthquake due to a dam is not unusual. After all, you are adding a lot of weight to that little area behind the dam.
Take a look at this article and decide for yourself if you want to add a word or two about that.
https://archive.internationalrivers.org/earthquakes-triggered-by-dams (https://archive.internationalrivers.org/earthquakes-triggered-by-dams)
Windmill kills birds, solar farm has its own drawback, nature doesn't give us anything for free I suppose.
--------------------------------------
Hey, good job there! We can refine till kingdom comes, but even if you don't include any of these round 2 improvements, there isn't much one can complain about.
I have incorporated most of the suggestions, but two of them in the form of a footnotes so as not to overload the amount of text in each section.
https://www.picuino.com/en/electric-energia.html#f1 (https://www.picuino.com/en/electric-energia.html#f1)
Thank you very much.
-
"Thermal energy
... ...
This statement bugs me since "degraded form" is not well defined. Bugs me, but I think I understand what you are saying.
...
I think "degraded form" is somewhat well defined especially in engineering and thermodynamics.
...
Appreciate the heads-up. Different perspectives brings different meaning to words. I stand now more educated.
-
The problem is that electrical energy and electrical power are interrelated concepts.
Electrical power can be defined as voltage times current, but that does not explain what it is. It can also be defined more intuitively as the amount of energy consumed per second.
Electrical energy on the other hand is defined as the total work done or the total heat generated, but its formula is power times time.
It seems difficult to explain one concept without the other. They must be explained at the same time, but you have to start somewhere.
I remember that I had a hard time understanding these two concepts at first because they were similar and related.
How would you explain these two concepts to someone who does not know anything about electrical power and energy?
Hello again,
One thing that helps i think is to understand that an understanding of mechanical energy is fundamental to an understanding of other forms of energy such as electrical energy. Various things can be explained with the use of the motion of something like an object or a particle. That's because all forms of energy break down into the motion of something. For example, one electron volt is when an electron moves though a field of 1 volt.
-
While all this is true, there is no such analogy for nuclear and radiant energy. In any case, I have given up trying to define energy. I think we all have an intuitive idea of what it is and in describing the different forms of energy I reinforce that intuitive idea. I don't want to go into more exact definitions which will always give problems and, besides, I don't need the students to know them at this age.
-
While all this is true, there is no such analogy for nuclear and radiant energy. In any case, I have given up trying to define energy. I think we all have an intuitive idea of what it is and in describing the different forms of energy I reinforce that intuitive idea. I don't want to go into more exact definitions which will always give problems and, besides, I don't need the students to know them at this age.
Isn't radiant energy the motion of particles?
I think gravity is the only remaining open question.
The ultimate answer is we only describe things in nature in relation to other things so no definition stands alone. To that end we describe energy in relation to matter with the seemingly ageless equality:
e=m*c^2
If you still have questions with respect to your target audience, just pick up an edition of a high school physics textbook.
-
Two ideas. First would be discuss force being invisible which applies to electric or more correctly electrostatic forces. Then a casual intro into 'work' and 'energy' concepts, like work = force X distance.
You could caution that the concept of 'work' when it is electricity or explicitly a current flow, that the matter flowing (electrons) isn't the real work, the real work is the force, being carried down the wire; confusing because both the fields and the currents flowing.
I think it may be same issue, with water flow, where the force of pressure does the work...unless I guess it's the case of water wheel buckets responding to gravity from the water mass.
-
A second concept, or group of concepts, is the complementary relation between inductance and capacitors.
Now, most advanced trainers know, it's ok to introduce some very advanced concepts, to a raw beginner,...much like a virtuoso violin teacher could have students take on material much more advanced, than beginning level. You just need to closely avoid overstressing or overwhelming the new student.
That's maybe like saying; "I'm going to play this piece, one of the most advanced harpsichord arrangements ever produced...so don't worry about getting the notes right, just enjoy for now...".
So the example I'd give after a brief mention of electric and magnetic fields, is an example radio frequency circuit capacitor, experiencing inductance by way of long-ish leads. Those capacitor leads, you'd say, are going to have inductance, and possibly cause an un-wanted resonance side-effect.
Notice those are pretty advanced ideas, but you just tell the student that, and let them start with questions there.
I got this idea while reading about Jim Williams application note #47, featured in the 'Technical Subject's section.
Student probably won't get all of the RF circuit things right away, but at least you can focus on 'self inductance' in the leads, to zoom in on some details, to teach.
Kind of like saying, to a mature student, here is the whole mess of details, but perhaps the worst it can be, learning for a while. Student can gaze up, and realize a good bit of learning is not so 'impossible'.
Ditto for teaching the Calculus. (I worked as a student tutor in college).
-
I love Jim Williams' application notes.
https://www.analog.com/media/en/technical-documentation/application-notes/an47fa.pdf (https://www.analog.com/media/en/technical-documentation/application-notes/an47fa.pdf)
The problem is that they are overly complex concepts and get away from the topic, which is to understand the sources of electricity generation and the electric bill.
-
Like to argue a tiny bit on that, although I see what you mean.
Starting with very basic concepts, is better off in some formal classroom, but in less formal venues, quoting OHM's Law gets to be boring and disconnected. Same thing with (isolated) components like a capacitor or inductor.
But I see your point, if it's electric power system; I think there I might explain what AC or alternating current is, and a couple of concepts involving transformers.
Also, could include gravity field example, of forces being invisible, but still active.
The Jim Williams notes would be in other context, of RF circuits.
-
...
Kind of like saying, to a mature student, here is the whole mess of details, but perhaps the worst it can be, learning for a while. Student can gaze up, and realize a good bit of learning is not so 'impossible'.
...
That is key right there. If it is one-to-one, the teacher can observe the reaction of the student and adjust accordingly. When one-to-many, that becomes more difficult.
Good music one can appreciate without knowing how do play it. One can enjoy "Swan Lake" (Ballet by Tchaikovsky) without even being able to stand on one's own feet. Science is rather different. Some would appreciate the wonder, others would "gaze" then shuts down. When "brain overloads" occurs, it may turn the student into rejecting the subject altogether.
Many (particularly the younger students) do not realize some questions can't be answered yet. Some has "current standard" answers but the answers require a lot of learning before it can be understood.
The wonders of nature... I believe the wonder will never stop. In the time of Archimede, one can perhaps learn all the Physics known to humans in a few years. That leaves a lot of time for a student to learn, then to research and expand the knowledge in the field. Knowledge have been expanding for centuries now and the expansion continues. There comes a point when the time the necessary to acquire the "foundational knowledge" for a sub-field consumes all the brain's productive years leaving no time to develop new knowledge for that sub-field. Then, advancement will stop -- unless human develops a way to acquire knowledge by other means rather than the time consuming method we called learning.
-
...
Kind of like saying, to a mature student, here is the whole mess of details, but perhaps the worst it can be, learning for a while. Student can gaze up, and realize a good bit of learning is not so 'impossible'.
...
That is key right there. If it is one-to-one, the teacher can observe the reaction of the student and adjust accordingly. When one-to-many, that becomes more difficult.
Good music one can appreciate without knowing how do play it. One can enjoy "Swan Lake" (Ballet by Tchaikovsky) without even being able to stand on one's own feet. Science is rather different. Some would appreciate the wonder, others would "gaze" then shuts down. When "brain overloads" occurs, it may turn the student into rejecting the subject altogether.
Many (particularly the younger students) do not realize some questions can't be answered yet. Some has "current standard" answers but the answers require a lot of learning before it can be understood.
The wonders of nature... I believe the wonder will never stop. In the time of Archimede, one can perhaps learn all the Physics known to humans in a few years. That leaves a lot of time for a student to learn, then to research and expand the knowledge in the field. Knowledge have been expanding for centuries now and the expansion continues. There comes a point when the time the necessary to acquire the "foundational knowledge" for a sub-field consumes all the brain's productive years leaving no time to develop new knowledge for that sub-field. Then, advancement will stop -- unless human develops a way to acquire knowledge by other means rather than the time consuming method we called learning.
Hello there,
That last paragraph is very interesting.
I always tell people not to take anything as written in stone when it comes to physics, because it is still evolving and has been for many years as you noted. Combined with this, i like to mention that when we look back at various notable figures like Newton, we see a smart person who made some keen observations and they were taken as fact and the absolute final answer on the problem at hand. Years later, many years, we find out it isn't exactly true even though it may work as a good approximation. Of course it was Einstein who changed that, and there is work now that suggests even that may not be the final answer. This begs the question, is there any final answer. It seems that all we ever do is 'render' nature into a theory, we don't actually know what nature really is completely. In that light it appears Science is just another religion in that we 'believe' certain things are true and righteous until we find out something else. Once we find out that something else, then that becomes the true and righteous dogma.
-
In electric power, there is little dogma and much opinion.
Just look at the endless discussions about nuclear production or the arguments for and against wind power.
Batteries to store the surplus of intermittent alternative energies also bring conflicts. The lithium runs out, they are very polluting or generate a fire risk impossible to extinguish, etc.
Fossil energies are also at the heart of many discussions. With the war in Ukraine, the supply of Russian natural gas to Europe has become a topic of endless debate.
On the subject of electricity production, and energy in general, it is difficult to give dogmas and it is very easy to fall into political opinions.
-
To nOObs, it's easier to grasp if it's somthing they can relate to, or use their imagination to further grasp the concept.
Take an (electric) space heater as example. There are small heaters that get a bit warm, and higher powered heaters that get really hot.
But at the end of the year, you have to pay for the energy, so the amount of hours that the heater is on does also count.
-
...
Kind of like saying, to a mature student, here is the whole mess of details, but perhaps the worst it can be, learning for a while. Student can gaze up, and realize a good bit of learning is not so 'impossible'.
...
That is key right there. If it is one-to-one, the teacher can observe the reaction of the student and adjust accordingly. When one-to-many, that becomes more difficult.
Good music one can appreciate without knowing how do play it. One can enjoy "Swan Lake" (Ballet by Tchaikovsky) without even being able to stand on one's own feet. Science is rather different. Some would appreciate the wonder, others would "gaze" then shuts down. When "brain overloads" occurs, it may turn the student into rejecting the subject altogether.
Many (particularly the younger students) do not realize some questions can't be answered yet. Some has "current standard" answers but the answers require a lot of learning before it can be understood.
The wonders of nature... I believe the wonder will never stop. In the time of Archimede, one can perhaps learn all the Physics known to humans in a few years. That leaves a lot of time for a student to learn, then to research and expand the knowledge in the field. Knowledge have been expanding for centuries now and the expansion continues. There comes a point when the time the necessary to acquire the "foundational knowledge" for a sub-field consumes all the brain's productive years leaving no time to develop new knowledge for that sub-field. Then, advancement will stop -- unless human develops a way to acquire knowledge by other means rather than the time consuming method we called learning.
Hello there,
That last paragraph is very interesting.
I always tell people not to take anything as written in stone when it comes to physics, because it is still evolving and has been for many years as you noted. Combined with this, i like to mention that when we look back at various notable figures like Newton, we see a smart person who made some keen observations and they were taken as fact and the absolute final answer on the problem at hand. Years later, many years, we find out it isn't exactly true even though it may work as a good approximation. Of course it was Einstein who changed that, and there is work now that suggests even that may not be the final answer. This begs the question, is there any final answer. It seems that all we ever do is 'render' nature into a theory, we don't actually know what nature really is completely. In that light it appears Science is just another religion in that we 'believe' certain things are true and righteous until we find out something else. Once we find out that something else, then that becomes the true and righteous dogma.
I was agreeing with you till your last point. I'll response in the order you have, we will get to the last point.
re: "...Of course it was Einstein who changed that..."
I largely agree with your point about Newton & Einstein. Einstein didn't "change it", it is more a refinement to account for speed of light not being infinite and when speed of objects in question is a significant percentage of light speed.
re: "...and there is work now that suggests even that may not be the final answer..."
That suggestion is not recent. Relativity and Quantum mechanics doesn't work together. The math just doesn't work (as in xyz divide by zero or infinite*xyz/infinity, that kind of "math blow up"). Both relativity and quantum mechanics are "proven". Proven here is defined as "it accurately describes nature and accurately predicts nature". They are each proven in their own realm, but as yet "Relativistic Quantum Mechanics" doesn't yet work.
re: "...This begs the question, is there any final answer...."
That would depend on what "final" means here.
This is not different than being a taxi-driver before GPS. You can have a taxi-driver who is familiar with NYC, but take him to San Francisco he could be totally lost. He will need a map of San Francisco instead of using the map of NYC inside his head.
Substitute NYC for "Newtonian", and San Francisco for "Relativistic". Physicist needs a new map (set of rules) for each realm. That two maps solution works independently yet correctly in their own realm. Do you consider that final? Or must we integrate the maps before we consider it final?
Now mix in the Quantum realm. Nature is not allowing us to integrate everything into one map for now, mixing quantum mechanics and relativity, the rules blew the math up. We may be able to find a way around that. So if integration into one map is part of being "final" than we are not there.
If I include the "very large" galaxy size. We know it is not working -- stars orbiting the galaxy are going too fast. So we introduce something which we call "dark matter" to explain/adjust that. Dark matter (in my opinion) is a kludge but may not be the right one. This is one realm we didn't know until recently. So even if we allow "final" to be "separate maps", we don't know what other realm(s) may be there. If they are unknown, we don't know to include them. So as most we can think of "final" is "work in all known realm(s) only".
re: "...In that light it appears Science is just another religion..."
This is where you and I depart from our agreement. Science is based on measurable criteria and repeatable measurements. Math is the means to express the relationship and rules to quantify.
V=IR. In that mathematical formula, I convey to you that the relationship observed is Voltage equals Current times Resistance. Applied the science and you can now describe and predict what happens to the Current if you double the Voltage while keeping Resistance the same. It is based on facts every practitioner can observe and validate.
Religion is based on faith. No observation or measurement is used. Doesn't mean it is wrong, it just mean you can't measure it or repeat it. Where as scientific laws and principals can be observed and measured at will (with equipment of course).
Here comes where my legs are getting shaky... My own reservations and doubts.
Now with "big science" like LHC (Large Hadron Collider) and LIGO (Laser Interferometer Gravitational-Wave Observatory), we moved away from something that every practitioner can observe and verify. There is only one LHC, and one pair of LIGO. Repeatability is an issue -- did you actually saw something or is that very very small signal random or an artifact of the way the system is functioning? Higgs particle discovery was "5 sigma". That is 1 in 3.5 million probability that the observed event is a random error. You can of course build your own LHC to satisfy "every practitioner can observe and repeat" but I can say with better than 5-sigma that it is NOT viable for the average EEVBlog members to build their own LHC.
Add to that, data filtering adjustment(s) is used and getting to raw data is not a readily available path. Adjusted enough, you can make the weather forecast radar signal look like a picture of Holy Mary or rings of Jupiter. So the guys getting the million(s) dollar grant(s) said they measured it. You decide if confirmation bias is an issue or not...
-
...
Kind of like saying, to a mature student, here is the whole mess of details, but perhaps the worst it can be, learning for a while. Student can gaze up, and realize a good bit of learning is not so 'impossible'.
...
That is key right there. If it is one-to-one, the teacher can observe the reaction of the student and adjust accordingly. When one-to-many, that becomes more difficult.
Good music one can appreciate without knowing how do play it. One can enjoy "Swan Lake" (Ballet by Tchaikovsky) without even being able to stand on one's own feet. Science is rather different. Some would appreciate the wonder, others would "gaze" then shuts down. When "brain overloads" occurs, it may turn the student into rejecting the subject altogether.
Many (particularly the younger students) do not realize some questions can't be answered yet. Some has "current standard" answers but the answers require a lot of learning before it can be understood.
The wonders of nature... I believe the wonder will never stop. In the time of Archimede, one can perhaps learn all the Physics known to humans in a few years. That leaves a lot of time for a student to learn, then to research and expand the knowledge in the field. Knowledge have been expanding for centuries now and the expansion continues. There comes a point when the time the necessary to acquire the "foundational knowledge" for a sub-field consumes all the brain's productive years leaving no time to develop new knowledge for that sub-field. Then, advancement will stop -- unless human develops a way to acquire knowledge by other means rather than the time consuming method we called learning.
Hello there,
That last paragraph is very interesting.
I always tell people not to take anything as written in stone when it comes to physics, because it is still evolving and has been for many years as you noted. Combined with this, i like to mention that when we look back at various notable figures like Newton, we see a smart person who made some keen observations and they were taken as fact and the absolute final answer on the problem at hand. Years later, many years, we find out it isn't exactly true even though it may work as a good approximation. Of course it was Einstein who changed that, and there is work now that suggests even that may not be the final answer. This begs the question, is there any final answer. It seems that all we ever do is 'render' nature into a theory, we don't actually know what nature really is completely. In that light it appears Science is just another religion in that we 'believe' certain things are true and righteous until we find out something else. Once we find out that something else, then that becomes the true and righteous dogma.
I was agreeing with you till your last point. I'll response in the order you have, we will get to the last point.
re: "...Of course it was Einstein who changed that..."
I largely agree with your point about Newton & Einstein. Einstein didn't "change it", it is more a refinement to account for speed of light not being infinite and when speed of objects in question is a significant percentage of light speed.
re: "...and there is work now that suggests even that may not be the final answer..."
That suggestion is not recent. Relativity and Quantum mechanics doesn't work together. The math just doesn't work (as in xyz divide by zero or infinite*xyz/infinity, that kind of "math blow up"). Both relativity and quantum mechanics are "proven". Proven here is defined as "it accurately describes nature and accurately predicts nature". They are each proven in their own realm, but as yet "Relativistic Quantum Mechanics" doesn't yet work.
re: "...This begs the question, is there any final answer...."
That would depend on what "final" means here.
This is not different than being a taxi-driver before GPS. You can have a taxi-driver who is familiar with NYC, but take him to San Francisco he could be totally lost. He will need a map of San Francisco instead of using the map of NYC inside his head.
Substitute NYC for "Newtonian", and San Francisco for "Relativistic". Physicist needs a new map (set of rules) for each realm. That two maps solution works independently yet correctly in their own realm. Do you consider that final? Or must we integrate the maps before we consider it final?
Now mix in the Quantum realm. Nature is not allowing us to integrate everything into one map for now, mixing quantum mechanics and relativity, the rules blew the math up. We may be able to find a way around that. So if integration into one map is part of being "final" than we are not there.
If I include the "very large" galaxy size. We know it is not working -- stars orbiting the galaxy are going too fast. So we introduce something which we call "dark matter" to explain/adjust that. Dark matter (in my opinion) is a kludge but may not be the right one. This is one realm we didn't know until recently. So even if we allow "final" to be "separate maps", we don't know what other realm(s) may be there. If they are unknown, we don't know to include them. So as most we can think of "final" is "work in all known realm(s) only".
re: "...In that light it appears Science is just another religion..."
This is where you and I depart from our agreement. Science is based on measurable criteria and repeatable measurements. Math is the means to express the relationship and rules to quantify.
V=IR. In that mathematical formula, I convey to you that the relationship observed is Voltage equals Current times Resistance. Applied the science and you can now describe and predict what happens to the Current if you double the Voltage while keeping Resistance the same. It is based on facts every practitioner can observe and validate.
Religion is based on faith. No observation or measurement is used. Doesn't mean it is wrong, it just mean you can't measure it or repeat it. Where as scientific laws and principals can be observed and measured at will (with equipment of course).
Here comes where my legs are getting shaky... My own reservations and doubts.
Now with "big science" like LHC (Large Hadron Collider) and LIGO (Laser Interferometer Gravitational-Wave Observatory), we moved away from something that every practitioner can observe and verify. There is only one LHC, and one pair of LIGO. Repeatability is an issue -- did you actually saw something or is that very very small signal random or an artifact of the way the system is functioning? Higgs particle discovery was "5 sigma". That is 1 in 3.5 million probability that the observed event is a random error. You can of course build your own LHC to satisfy "every practitioner can observe and repeat" but I can say with better than 5-sigma that it is NOT viable for the average EEVBlog members to build their own LHC.
Add to that, data filtering adjustment(s) is used and getting to raw data is not a readily available path. Adjusted enough, you can make the weather forecast radar signal look like a picture of Holy Mary or rings of Jupiter. So the guys getting the million(s) dollar grant(s) said they measured it. You decide if confirmation bias is an issue or not...
Hi,
I don't have the time or patience to reply to a lot of points at the same time, but the one that strikes me is your comment about Einstein vs Newton.
I hear this from time to time, that Einstein is just a 'refinement' on Newton. That's entirely and completely wrong, and i don't think there is anything quite as wrong as that.
It was not a 'refinement' it was a total and complete paradigm change. Newton based his calculation on pure algebra and a simple observation. Einstein changed that entirely by showing that gravity is a property of spacetime, something Newton had absolutely no idea about.
The 'refinement' is just a nice coincidence which makes it possible to calculate things that were not known at the time of Newton or at least not studied. In fact, Newton could have not calculated some things that Einstein could so it wasn't like Einstein got a better numerical result, he got a completely better understanding and was capable of MORE results that Newton never could.
But my point was not to bring this into careful scrutiny, it was just to show how much things can change. Is it the end of all ends? I don't think so, and if you consider some of the more recent ideas that have been coming up it may never be possible to understand the root causes of Nature, and part of that may be because the Universe is evolving itself. That would mean that there are things we can not know right now because they don't even exist yet. Only after they come into being will we be able to examine them and see what we can figure out. The question that comes up then is of course can we figure out how it is evolving? That may be possible some day, but we don't even have one clearly known example yet so it's going to be a long, long, way off.
Just to recap, for example it is not that Newton got a numerical result of say 1.235 and Einstein got a result of 1.2345 (which rounds to 1.235), Einstein came up with a completely different way of thinking about the Nature of gravity. In fact, he may have gotten the same result 1.235 but the WAY and the REASON he got that was because of a completely different set of ideas. I'm sure i don't have to go into detail about his theories, which are far from what Newton came up with. The level of understanding changed by leaps and bounds.
Oh one more little thing and i quote:
"Religion is based on faith. No observation or measurement is used. Doesn't mean it is wrong, it just mean you can't measure it or repeat it. Where as scientific laws and principals can be observed and measured at will (with equipment of course)."
See with that i can see you did not understand my point at all. The point was that since the measurements and conclusions are time stamped and can change in the future, it is still a 'belief'. It's not like gravity is going to disappear, but our understanding of it will change and thus what we believe right now is very likely not correct in its entirety. That's very similar to a religion. It's not like religion is wrong either though I'm not saying that.
Also, you can see the arguments on both sides of some quantum physics ideas. Diametrically opposed. Remind you of anything? Yes, religion (chuckle).
A. Do we have one universe or many universes (may worlds).
B. Do we have one God or many Gods.
etc., etc. (chuckle).
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...
I hear this from time to time, that Einstein is just a 'refinement' on Newton. That's entirely and completely wrong, and i don't think there is anything quite as wrong as that.
It was not a 'refinement' it was a total and complete paradigm change. Newton based his calculation on pure algebra and a simple observation. Einstein changed that entirely by showing that gravity is a property of spacetime, something Newton had absolutely no idea about.
...
There are occasions I took the exact same position as yours above. On this occasion, I choose to use a gentler description. Net net is the same.
I would argue the "gravity is a property of spacetime" bit, but until we truly understand what is space and what is time, argument is a bit premature. I like to see more work on fundamentals -- such as, where did big-G (universal gravitational constant, not little-g which is earth's gravity on the surface).
Then again, may be life will be very boring if there is no fundamental unknowns left...
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...
I hear this from time to time, that Einstein is just a 'refinement' on Newton. That's entirely and completely wrong, and i don't think there is anything quite as wrong as that.
It was not a 'refinement' it was a total and complete paradigm change. Newton based his calculation on pure algebra and a simple observation. Einstein changed that entirely by showing that gravity is a property of spacetime, something Newton had absolutely no idea about.
...
There are occasions I took the exact same position as yours above. On this occasion, I choose to use a gentler description. Net net is the same.
I would argue the "gravity is a property of spacetime" bit, but until we truly understand what is space and what is time, argument is a bit premature. I like to see more work on fundamentals -- such as, where did big-G (universal gravitational constant, not little-g which is earth's gravity on the surface).
Then again, may be life will be very boring if there is no fundamental unknowns left...
Hi,
Yeah i know what you mean, did we look at it this year, last year, or next year ha ha.
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...
I hear this from time to time, that Einstein is just a 'refinement' on Newton. That's entirely and completely wrong, and i don't think there is anything quite as wrong as that.
It was not a 'refinement' it was a total and complete paradigm change. Newton based his calculation on pure algebra and a simple observation. Einstein changed that entirely by showing that gravity is a property of spacetime, something Newton had absolutely no idea about.
...
There are occasions I took the exact same position as yours above. On this occasion, I choose to use a gentler description. Net net is the same.
I would argue the "gravity is a property of spacetime" bit, but until we truly understand what is space and what is time, argument is a bit premature. I like to see more work on fundamentals -- such as, where did big-G (universal gravitational constant, not little-g which is earth's gravity on the surface).
Then again, may be life will be very boring if there is no fundamental unknowns left...
Hi,
Yeah i know what you mean, did we look at it this year, last year, or next year ha ha.
By the way, I missed a few words in the line before the last line... "where did big-G..." should really be "where did big-G came from..."
Next year is too soon.
One of my Physics Professor once told a joke in class: After (Wolfgang) Pauli died, he went to heaven and met God. Pauli asked "Where and how the Fine Structure Constant came to be?" God told him. Pauli than proceed to explain to God why that couldn't be right.
Whether that joke was funny or not, we sure need more theoretical Physicist like Wolfgang, Eisenstein, Dirac... Fine Structure Constant is still as mysterious as when Pauli died.
Next year is too soon. We have not been making much progress in the fundamentals. May be because String Theory sucked all the oxygen. May be we just want to do things we already know how (experimental Physics, just building bigger ones) , may be we are not as smart. Either way, we didn't make much progress in the theoretical front.
-
...
I hear this from time to time, that Einstein is just a 'refinement' on Newton. That's entirely and completely wrong, and i don't think there is anything quite as wrong as that.
It was not a 'refinement' it was a total and complete paradigm change. Newton based his calculation on pure algebra and a simple observation. Einstein changed that entirely by showing that gravity is a property of spacetime, something Newton had absolutely no idea about.
...
There are occasions I took the exact same position as yours above. On this occasion, I choose to use a gentler description. Net net is the same.
I would argue the "gravity is a property of spacetime" bit, but until we truly understand what is space and what is time, argument is a bit premature. I like to see more work on fundamentals -- such as, where did big-G (universal gravitational constant, not little-g which is earth's gravity on the surface).
Then again, may be life will be very boring if there is no fundamental unknowns left...
Hi,
Yeah i know what you mean, did we look at it this year, last year, or next year ha ha.
By the way, I missed a few words in the line before the last line... "where did big-G..." should really be "where did big-G came from..."
Next year is too soon.
One of my Physics Professor once told a joke in class: After (Wolfgang) Pauli died, he went to heaven and met God. Pauli asked "Where and how the Fine Structure Constant came to be?" God told him. Pauli than proceed to explain to God why that couldn't be right.
Whether that joke was funny or not, we sure need more theoretical Physicist like Wolfgang, Eisenstein, Dirac... Fine Structure Constant is still as mysterious as when Pauli died.
Next year is too soon. We have not been making much progress in the fundamentals. May be because String Theory sucked all the oxygen. May be we just want to do things we already know how (experimental Physics, just building bigger ones) , may be we are not as smart. Either way, we didn't make much progress in the theoretical front.
Yeah i hear ya on that. That joke is cute too.
Ive been waiting for more on quantum entanglement, gravity, fusion, AI, and new Columbo episodes.