Oscilloscope question #2

[Russ]

A 6.2 Ohm Resistor and a 100 mH inductor are connected in series, across a 10 Vpp, 9.87 kHz sine wave  power source. What is the impedance of the circuit?

What is the phase angle, theta, of the circuit?

A. 45 degrees
B. 0 degrees
C. 60 degrees
D. 90 degrees

Thanks

[rstofer]

89.94 degrees
Again:
http://keisan.casio.com/exec/system/1258032600

[Russ]

89.94 degrees
Again:
http://keisan.casio.com/exec/system/1258032600

Thank you. I have to track down that Math app.

Thanks

[tggzzz]

89.94 degrees
Again:
http://keisan.casio.com/exec/system/1258032600

Thank you. I have to track down that Math app.

No you don't.

You have to understand the theory of parallel and series impedances, plus complex arithmetic. Then you will be able to use any old calculator to solve the problem, including calculators you are allowed to have in exams.

More importantly, you will get a gut feel for what's happening, and will then be in a good position to understand how circuits work, and when calculators and simulators are giving invalid answers.

[rstofer]

The formulas are in terms of Henries and Ohms.  Be careful about that!  Omega comes from 2 * PI * freq in Hz.

Plug the numbers into the equations and see what you get.  I didn't do that because I am lazy.  Also, it's not my homework.

The best way to learn this stuff is to solve problems.  You have a problem, you have the equations and, best of all, you have the solution.  Grab up a calculator and work it out!

[Russ]

89.94 degrees
Again:
http://keisan.casio.com/exec/system/1258032600

Thank you. I have to track down that Math app.

I really hope so. I really struggle with this stuff. I feel like such an idiot when it comes to these equations. 😬

Thanks

No you don't.

You have to understand the theory of parallel and series impedances, plus complex arithmetic. Then you will be able to use any old calculator to solve the problem, including calculators you are allowed to have in exams.

More importantly, you will get a gut feel for what's happening, and will then be in a good position to understand how circuits work, and when calculators and simulators are giving invalid answers.

[Russ]

The formulas are in terms of Henries and Ohms.  Be careful about that!  Omega comes from 2 * PI * freq in Hz.

Plug the numbers into the equations and see what you get.  I didn't do that because I am lazy.  Also, it's not my homework.

The best way to learn this stuff is to solve problems.  You have a problem, you have the equations and, best of all, you have the solution.  Grab up a calculator and work it out!

Thanks. I keep working on it. But I have difficulty with mathematical equations. And I just cannot seem to retain the knowledge. Very frustrating 😬

Thanks

[rstofer]

I don't have to remember the formulas, I just need to remember where to find them.  Google links to all of human knowledge - they're out there somewhere.

I'm working with my grandson on Calculus I.  Every time I come across an important concept, I write it on a 3x5 index card.  I remember that I wrote it and I remember that it's on an index card, all I have to do is thumb through the deck.

I had thought to use colored cards and separate concepts by color:  Trig : yellow, Limits : pink, Derivatives : green, Antiderivatives : white.  Something like that...

The index card is a workable concept for EE as well.

[Russ]

I don't have to remember the formulas, I just need to remember where to find them.  Google links to all of human knowledge - they're out there somewhere.

I'm working with my grandson on Calculus I.  Every time I come across an important concept, I write it on a 3x5 index card.  I remember that I wrote it and I remember that it's on an index card, all I have to do is thumb through the deck.

I had thought to use colored cards and separate concepts by color:  Trig : yellow, Limits : pink, Derivatives : green, Antiderivatives : white.  Something like that...

The index card is a workable concept for EE as well.

Interesting. I may go that route too. 👍

Thanks

[Mukrakiish]

I don't have to remember the formulas, I just need to remember where to find them.  Google links to all of human knowledge - they're out there somewhere.

I'm working with my grandson on Calculus I.  Every time I come across an important concept, I write it on a 3x5 index card.  I remember that I wrote it and I remember that it's on an index card, all I have to do is thumb through the deck.

I had thought to use colored cards and separate concepts by color:  Trig : yellow, Limits : pink, Derivatives : green, Antiderivatives : white.  Something like that...

The index card is a workable concept for EE as well.

+1 to that. When I was taking Engineering, there was pages of formulas per course. Combined between them all there was a small book of just formulas to deal with (never mind the concepts), same idea as what rstofer is saying...basically keeping a tome of formula with key points as to the "what" and "why" for that particular formula helps the most.

[rstofer]

There's another reason for the index cards:  Creating crib sheets.

At various times throughout the semester there are quizzes and exams.  Other than the Final, these will cover specific sections of the material and crib sheets are allowed.  So, we sort the index cards by topic and copy over the important formulas to an exam specific crib sheet.

This may turn out to be more practical than having the same information in a notebook.  We'll see...

There's a reason that everybody remembers Ohm's Law and it's not just because it is simple.  It's because it is used all the time.  Nothing happens in electronics without Ohm's Law.  The series RL formula isn't difficult, it's just hard to remember because it doesn't get the same attention as Ohm's Law.  I suspect if a person used the formula a few hundred times before breakfast it would be as ingrained as Ohm's Law.

Solve problems!  That's the only way to learn the material.

[Old Printer]

I never got the idea of taking notes in class, then rewriting them legibly that evening at home... so I didn't do it much   and my grades and knowledge showed the results.  Now some 50 odd years later I am trying to teach myself the same stuff again, this time because I want to know it. Big difference. Now I understand that after writing it two or three times you are 80% of the way to remembering it without the notes, until age catches up with you and you can't seem to remember anything

[tggzzz]

I never got the idea of taking notes in class, then rewriting them legibly that evening at home... so I didn't do it much   and my grades and knowledge showed the results.  Now some 50 odd years later I am trying to teach myself the same stuff again, this time because I want to know it. Big difference. Now I understand that after writing it two or three times you are 80% of the way to remembering it without the notes, until age catches up with you and you can't seem to remember anything

The first part matches my experience 

So does the second part 

[Hextejas]

I don't have to remember the formulas, I just need to remember where to find them.  Google links to all of human knowledge - they're out there somewhere.

I'm working with my grandson on Calculus I.  Every time I come across an important concept, I write it on a 3x5 index card.  I remember that I wrote it and I remember that it's on an index card, all I have to do is thumb through the deck.

I had thought to use colored cards and separate concepts by color:  Trig : yellow, Limits : pink, Derivatives : green, Antiderivatives : white.  Something like that...

The index card is a workable concept for EE

I am a total beginner to this and was wondering what did you ask google so as to be able to find that formula ? I am going to try to solve it.
This is a real challenge to me as the most math I had was in high school. I am not a dummy but have never been exposed to it.
I do remember Ohms law however 😁
I am also trying to learn how to use a scope and from this thread it seems like the slope of the trace is also important besides the amplitude and frequency. No need to explain why as I will eventually get to it. Just let me know that I need to pay attention to it.
My area of interest is audio and building a better stereo.

Thanks

[rstofer]

'series RL circuit calculator' without the quotes

Second reply was the one I picked because the first one was for a series R-L-C circuit.

[Russ]

I am just learning how to use the Scope, and with mathematical equations being a weakness of mine, I struggle with it.

Thanks

[rstofer]

You have a perfectly good example problem.  You have the equations, you have the required data and you have a calculator.  It is a good exercise to see if you can get the same answer.

In effect, that's how we all learned this stuff.  The book had the explanation and perhaps a couple of examples and there were problems at the end of the chapter.  In many cases, the odd numbered problems had answers in the back of the book.  Only the even numbered problems were assigned as homework but we could use the very similar odd numbered problems to convince ourselves we knew how to solve the even numbered problems.

Watch some of Dave's tutorial videos.  He has a couple (or more) on op amps:


One on node and mesh analysis - Ohm's Law and Kirchhoff's Laws


There's a lot of material on the Internet.

Here's a fairly extensive program on circuits:
https://learn.digilentinc.com/classroom/realanalog/