I wish academia took more time to explain things in digestible way instead of dumping loads of dry papers in rigorous form. For instance, my life would be so much easier if I saw just this thing below [1]. Alternating current described in complex numbers has so much sense after going through that material.
Why is electricity so hard to understand? (1989)
111–120 of 216 posts
Re: Why is electricity so hard to understand? (1989)
#112Earlier quoted context omitted.
The irrational part of this is that the 'wrench system' is actually sized in 32nds of an inch, and thus would be much easier to comprehend with 'improper fractions'. 4/32, 5/32, 6/32, 8/32 ... etc
Or just "size 4, size 5", etc, with the "/32" as overall metadata
Except that there are wrench sizes in the /64 range as well.
Re: Why is electricity so hard to understand? (1989)
#113I've always been bemused by EE wallet cards that contain: V = IR I = V/R R = V/I If an EE does not know this formulas, he isn't an EE. If he understands so little about algebra that he needs the three forms, he's going to be misusing the formula.
What?! No power factor formula?
Re: Why is electricity so hard to understand? (1989)
#114I think more than half the time I spent earning my EE degree has been spent unlearning the intuitive (but wrong) things that I was liberally taught. I was fortunate enough to have an exceptional Physics teacher in high school, who managed to avoid a lot of the bullshit that less fortunate students were fed; sadly, I compensated that with some of my own (misguided) self-study. This experience also taught me to activel…
Great point that's really deep.
One of the devilish things about science is that the mental abstraction model that works for a layperson doesn't really scratch the surface.
Re: Why is electricity so hard to understand? (1989)
#115Earlier quoted context omitted.
Ah . That's a terminology fuck-up on my side, then. I've never encountered this convention, but classical electromagnetism has almost two centuries of history behind it. A lot of weird names have been used for a lot of things. For what it's worth, though, these are terrible names, archaic or not :-D. If they ever were in use, I'm glad we moved on.
I'm not sure they are terrible. Electrostatic describes charges at rest, capable of inducing a voltage across a dielectric. Electrodynamic describes charges in motion, capable of inducing a current across a conductor. They seem like apt descriptions to me.
It doesn't sound too bad when you put it that way, and it certainly made sense back when Ampere introduced the term, but:
* It doesn't match the way we define electrostatics, magnetostatics and electrodynamics. What defines electrodynamics isn't the fact that charges are moving (they're moving if the currents are constant, too, but the magnetic fields produced by steady currents are in magnetostatics' yard) but the interaction of charges and currents (in more formulaic terms, when both charge densities and current densities are present, not only do you get both electric and magnetic fields, as in magnetostatics, but they also vary in time).
* Charges in motion still produce a voltage across a dielectric. Calling the electric field they produce "electrostatic" when the charges are moving and the field is certainly not static.
Re: Why is electricity so hard to understand? (1989)
#116Earlier quoted context omitted.
I think you are missing the point of the water analogies. It is what made electricity make sense to me as well. But don't take it too literally, it's an analogy, not an identity. If you start with things like "a motor is like a turbine, a generator is like a pump, a battery is like an elevated tank", a lot of things can fall into place. The point is you can visualize it.
It's hardly fair to say that water analogies are good but "capacitors store charge" is bad, they are both weak analogies
There's nothing weak about saying capacitors store charge. That's exactly what they do. You measure charge in coulombs, which is how you count electrons. Capacitance is just the value that relates stored coulombs of charge to available voltage.
Re: Why is electricity so hard to understand? (1989)
#117Earlier quoted context omitted.
Intuitive but wrong (and doggedly persistent) idea #1: "electric current is moving electrons". It is moving photons, exciting (largely) stationary electrons. I can't stress how crucial overcoming that misconception was when I was doing EE.
Ehhhhh. Not really. It is the rate of charge passing through a cross-section. That's how it's defined, and as an EE student, what you're saying made little-to-no sense to me.
And the boson that mediates "charge" is....?
Re: Why is electricity so hard to understand? (1989)
#118Electromagnetics becomes much more elegant when cast in the language of differential forms. See e.g. [1]. [1] http://www.uio.no/studier/emner/matnat/fys/FYS4160/v08/under...
You can also go the fields route like Feynman would:
Re: Why is electricity so hard to understand? (1989)
#119Earlier quoted context omitted.
I got it taught about 3 or 4 times, and every time I understood it less. In middle school they told me, it's electrons moving at the speed of light through a conductor. In high school they told me, no no, they don't move at the speed of light, just when one electron enters the conductor, another one on the other side will leave the conductor, like with peas in a straw. And this enter/leaf is at the speed of light. At…
The first chapter explained it well. There are three different concepts that were all thrown under the umbrella term "electricity". >..little use by educators of the wind/sound electrical analogy: >AIR is a physical substance. >SOUND is a wave that propagates rapidly through a volume of air. >WIND is a flowing motion of air already present. >ELECTRIC CHARGES are a physical substance. >ELECTRIC ENERGY is a wave that t…
> ">ELECTRIC ENERGY is a wave that travels via a column of charge."
I'm not an expert when it comes to electricity, so someone correct me if I'm wrong, but one thing that has made sense to me when it comes to trying to understand electricity is that not all electrons have equal potential for work.
When studying electricity, you're often told the charge of an electron as a fixed quantity. However, if I've understood correctly, the work that an electron can do in conducting electric energy is not wholly described by the charge of the electron, it's also important to know the relationship that the electron has with the nucleus of the atom it orbits (i.e. the 'shelf' it's on).
To explain in another way, this analogy may be 'wrong' but I think it helps to think of electrons as capable of more work when they are less tightly coupled from the nucleus of an atom. The electrons that can do the most work are those in the outermost orbit of an atom. Whilst it may be wrong to say outer electrons are more charged than inner electrons, I think it might help in terms of visualisation. Again, correct me if I'm wrong.
Re: Why is electricity so hard to understand? (1989)
#120This article is amazing. It helped me to understand things that I were confused about years ago.
Whole website is filled (!) with these kind of articles http://amasci.com/ele-edu.html !