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"Veritasium" (YT) - "The Big Misconception About Electricity" ?
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bsfeechannel:

--- Quote from: dunkemhigh on March 23, 2022, 11:32:27 pm ---Blimey, and they couldn't even number the ports sequentially. The mere thousands of dollars ones probably leave the labels off.

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They're not oscilloscope channels.
HuronKing:

--- Quote from: penfold on March 24, 2022, 12:22:29 am ---
--- Quote from: HuronKing on March 23, 2022, 09:19:22 pm ---[...]
Now this I absolutely agree with. The difficulties are in the pedagogy. sqrt(-1) is called an 'imaginary' number or a 'complex' variable but these names are strictly historical. We can blame Rene Descartes for coining the term 'imaginary' as a derogatory term to imply they are not useful numbers. Those names have no bearing on what the sqrt(-1) actually represents - and it IS a physical phenomena. It's no less 'real' than negative numbers are 'real...' or how some ancient mathematicians regarded zero as a meaningless number...

Like, what if I asked you to calculate the power supplied by a voltage source? But then you did everything right and discovered the value of the wattage is negative! Is that not a 'real' answer? Of course it is. All it means is that I tricked you in the problem statement - the voltage source is absorbing power instead of delivering power.
[...]

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Nice try... maths just isn't that simple. It is kinda unrelated to negative and zero numbers: the algebra and arithmetic of real numbers and vectors as we know them today are defined, metric spaces, isomorphisms, and all that are properly axiomatically defined; the ancient interpretations were more from ill-formed and contentious philosophical bases which would lead to a disagreement. In contrast to that, the 'imaginary' unit, more generally, abstractly-describes translations between the mathematical representations of two 'real' quantities, e.g. phase angle... the imaginary unit is in itself not a physical quantity.

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This is veering really close to the question of "is mathematics physical?" and that's a big question!  :D

I'm saying that the terminology associated with 'imaginary' numbers is something we inherited from ancient mathematicians who didn't really know what they were dealing with - we got over it with negative numbers and zero, but sqrt(-1) is still something to be struggled with by students. I don't actually blame the ancient mathematicians - it's just unfortunate their prejudices about how to philosophically interpret these definitions have cursed students of today who hear something like 'imaginary numbers' versus 'real numbers' and assume these labels, by themselves, have something to do with physicality. They don't, at least in my opinion.  :)

In the case of electric circuits, we know the impedance of an inductor is Z = jwL and the impedance of a capacitor is Z = 1/jwC (thanks Steinmetz!)

Those impedances have physical effects and meaning on our circuits even though they have a weird looking j out in front. And while it is challenging to learn it's not so mysterious. As you said, it just means the incident current and incident voltage undergo a phase shift in time.
bsfeechannel:

--- Quote from: adx on March 19, 2022, 03:36:25 am ---Would it have been doomed to also replicate "until then engineers could only produce boat anchors" had Bardeen not suggested surface states? Was he a 'proper' physicist, or an electrical engineer who went back to do some physics papers - or someone above classification, and the transistor was waiting for him and his particular set of interests?

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John Bardeen had a degree in electrical engineering, but he took all the graduate courses in physics and mathematics that had interested him, and he graduated in five years instead of the usual four.

After that he applied and was accepted to the graduate program in mathematics at Princeton University. Then as a graduate student, Bardeen studied mathematics and physics. Under physicist Eugene Wigner, he ended up writing his thesis on a problem in solid-state physics.

At Harvard University, he worked with to-be Nobel laureates in physics John Hasbrouck van Vleck and Percy Williams Bridgman on problems in cohesion and electrical conduction in metals, and also did some work on level density of nuclei. He received his Ph.D. in mathematical physics.

As you can see, Bardeen was a full fledged physicist and went on to win TWO Nobel Prizes in advanced hacking.


--- Quote ---And again, did physicists not have that same four decades to come up with the transistor?
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Yes. And when the opportunity presented itself, they were prepared for the challenge. Engineers were not.


--- Quote ---When analysing that situation, the effect you want to confirm seems lost in the noise and bias, and only one thing shines through (apart from cleverness persistence and teamwork of course): The almighty dollar.
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No surprise, here. Science costs money. That's the whole point of the Nobel Prize.


--- Quote ---If this thread has shown us anything, it is that most electronics engineering is devoid of any direct use of physics and math,
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This thread has shown that electronics engineering devoid of math and physics reduces to a bunch of stupid misconceptions and dogmas bordering pseudo-science.
adx:
j: It did get me thinking about the 'reality' of the unitary minus operator. It isn't 'real' either: I am quite within my rights as an engineer to answer the power supply question as "it isn't delivering power" or "it delivers no power" or perhaps "it delivers zero power, but...".

Unitary minus is a thing, not a number. It represents the taking away of something, a negative number is composed of this thing and a quantity. Zero has no thing, and no quantity. I can consider negative numbers to be real, but they are as unreal as zero. They work together though very nicely to model the behaviour of quantities, as do rational and irrational numbers. They can be treated as a continuous sequence.

Complex numbers are composed of (up to) 2 things and 2 quantities. They can't be ordered. Phasors add to that an assumption of a sine wave.

I didn't for a moment suggest that reactance has no physical reality - just the square root of minus one as a descriptor.

I forgot to mention, that my position is essentially that i <> j.

I stand my ground firm, on the grounds that it is firm and unyielding.
bsfeechannel:

--- Quote from: adx on March 23, 2022, 11:05:16 pm ---bsfeechannel: Seen your post come in. Yes j appears in a couple of places, as an annotation. I was thinking of cheap ass VNAs and Smith charts when I made my claim.

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Let me get this straight. Because j doesn't appear explicitly on the VNA display, does it mean it is not there? Isn't the display representing a two-dimensional vector space? Aren't VNAs, VECTOR Network Analyzers?

Your point seems moot.
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