[aivisol]

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 random thought, without research.

[lilgreenland]

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 more thing to add. Electron drift velocity isn't the same as signal propagation speed. Wires can transmit information at around 2/3 the speed of light, but the drift velocity of an electron in a wire is around walking speed.

[jacquesm]

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.

[lilgreenland]

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...

[TeMPOraL]

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

[lilgreenland]

HA!

[jacquesm]

> 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' :)

[aivisol]

Thanks, point taken. And of course there are approximations and simplifications necessary when you try to explain this subject to high school students. I mean, that is the age when you still draw parallels from the physical world and it is easier to digest electron as a very small fast moving "ball" even though it is probably not.

[sandworm101]

Electrons move at the same speed. In a low-resistance material (metal crystal) they move in an almost strait line. In a higher resitance material they take a longer path, and must line up (stop) to make it through bottlenecks. They only seem to be moving more slowly at a macroscopic level.