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What Is Electricity? (2013)

learn.sparkfun.com

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Re: What Is Electricity? (2013)

#31
post #12

It's interesting to me when I read it. We take it down to the proton neutron and electron stating they are charged with positive negative or neutral charge.... but what are they charged with ? Electricity ? What is it made of ?

We say that a macroscopic body is “electrically charged” when there is an excess (or a lack) of electrons in it - which merely creates a disbalance between the electrons and the protons. We say that an elementary particle is electrically charged to indicate that there is a nonzero probability of it emitting or absorbing a photon (which leads to creation of the electromagnetic force).

Re: What Is Electricity? (2013)

#32

For an exercise in clear (and perhaps provocative) thinking, try: 'What Is "Electricity"?' ©1996 William J. Beaty > What is electricity? This question is impossible to answer because the word "Electricity" has several contradictory meanings. These different meanings are incompatible, and the contradictions confuse everyone. If you don't understand electricity, you're not alone. Even teachers, engineers, and scientist…

Analyzing the meaning of words is characteristic to philosophy and is not a sign of “clear thinking.”

Re: What Is Electricity? (2013)

#33
post #27

Earlier quoted context omitted.

Your notes are awesome. One thing I never thought of (and still have a doubt): can you really say that adding more resistance physically slows down the electrons? I mean, how slow can you make them move then by adding mega or giga ohm resistors? In metres per second? Isn't it more like that by adding more resistors there are less electrons which are able to pass it, which makes current flow less (not slower)? Just a…

I'm also speculating here, but I think resistance can manifest as slower electrons or as fewer electrons moving at the same speed. On the wire, away from the resistors, the number of electrons that can move should stay constant, so the election drift velocity should drop as resistance increases. https://en.wikipedia.org/wiki/Drift_velocity https://codepen.io/lilgreenland/pen/xprGvr (not a mobile friendly link) One mo…

The analogy I use to explain this (which is, like all analogies of course broken at many levels): a tube full of marbles will produce a marble at the far end every time you push one new marble in, but the individual marbles travel really slow.

Re: What Is Electricity? (2013)

#34

Earlier quoted context omitted.

I'm also speculating here, but I think resistance can manifest as slower electrons or as fewer electrons moving at the same speed. On the wire, away from the resistors, the number of electrons that can move should stay constant, so the election drift velocity should drop as resistance increases. https://en.wikipedia.org/wiki/Drift_velocity https://codepen.io/lilgreenland/pen/xprGvr (not a mobile friendly link) One mo…

The analogy I use to explain this (which is, like all analogies of course broken at many levels): a tube full of marbles will produce a marble at the far end every time you push one new marble in, but the individual marbles travel really slow.

I used to use the scene in "the two towers" where they light the fire to let Rohan know that Gondor is in need of aid. I thinks I have to stop referencing Lord of the Rings because most high schoolers haven't seen the movie these days.

https://www.youtube.com/results?search_query=beacons+of+mina...

Re: What Is Electricity? (2013)

#35
post #12

It's interesting to me when I read it. We take it down to the proton neutron and electron stating they are charged with positive negative or neutral charge.... but what are they charged with ? Electricity ? What is it made of ?

[deleted]

Re: What Is Electricity? (2013)

#36

Earlier quoted context omitted.

The analogy I use to explain this (which is, like all analogies of course broken at many levels): a tube full of marbles will produce a marble at the far end every time you push one new marble in, but the individual marbles travel really slow.

I used to use the scene in "the two towers" where they light the fire to let Rohan know that Gondor is in need of aid. I thinks I have to stop referencing Lord of the Rings because most high schoolers haven't seen the movie these days. https://www.youtube.com/results?search_query=beacons+of+mina...

> I thinks I have to stop referencing Lord of the Rings because most high schoolers haven't seen the movie these days.

I'm old enough to remember when they were 'just' books... and I thought you were going to write 'most high schoolers havne't read the books' :)

Re: What Is Electricity? (2013)

#37

I teach high school physics. Here's my notes/textbook on electricity with simulations and equations rendered in LaTex. https://landgreen.github.io/physics/notes/circuits/electrici...

Beautifully presented! Thanks for sharing, these notes are inspiring, I especially like the simplicity of the presentation's design paired with interactive elements. Too often I find material with the latter to be extremely busy. As someone interested in instruction, I'm taking notes from this!

Re: What Is Electricity? (2013)

#38
post #12

It's interesting to me when I read it. We take it down to the proton neutron and electron stating they are charged with positive negative or neutral charge.... but what are they charged with ? Electricity ? What is it made of ?

Physics runs out of "why"s somewhere around the question-asking ability of a clever 5-year-old, and becomes "here's the math to describe what happens" the rest of the way. Electric charge and all the other forces (AFAIK) just are.

Re: What Is Electricity? (2013)

#39
post #24

Earlier quoted context omitted.

A couple things off the top of my head from teaching high school physics: It would make the direction of current the same as the flow of charge. It would make electric fields predict the force on electrons. It would make the right-hand rule for magnetic fields work for electrons and instead of the left-hand rule.

But existing theory predicts all those just fine, it just happens that some things are not in the same direction, but it’s not like one can ignore direction. The math is still always there. And I argue things going in different directions is a feature, not a bug, because it reinforces the point that net charge and net particles are not the same thing.

Right, the math is the same. We face this in physics all the time. You drop a ball and it accelerates downward. Should the distance it covers be a negative number? Well, it seems linear distance should be positive, but if it is, then does down become positive? Shouldn't up be positive? Or do we reverse from end-minus-start and make it start-minus-end?

It doesn't matter. The math is all the same with just different labeling conventions.

For the general physics of electric charges, the convention that a proton is +1 and electron is -1 is somewhat useful as a reminder of the larger range of phenomena: protons carry charge, too, and a movement of positively charged molecules makes the charge carriers and current move in the same direction.

But as soon as you start working with practical, artificial electrical circuits (as opposed to, say, neurons), the electron-is-negative is a nuisance, because the charge carriers are almost always simple electrons. To visualize "stuff" moving one way, you have to visualize "other stuff" moving the opposite direction. You have to keep thinking that when you add more you get less. Visualization of electric/electronic technology would have been a lot more convenient if the convention had been that electrons were positive, protons negative.

Re: What Is Electricity? (2013)

#40

Earlier quoted context omitted.

The analogy I use to explain this (which is, like all analogies of course broken at many levels): a tube full of marbles will produce a marble at the far end every time you push one new marble in, but the individual marbles travel really slow.

I used to use the scene in "the two towers" where they light the fire to let Rohan know that Gondor is in need of aid. I thinks I have to stop referencing Lord of the Rings because most high schoolers haven't seen the movie these days. https://www.youtube.com/results?search_query=beacons+of+mina...

At least you aren't referencing the Twilight Bark from 101 Dalmatians - https://www.youtube.com/watch?v=xp-DW-2bq2U.
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