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Except in extremely exceptional circumstances, it is not useful to try to reason about the behavior of electrons when looking at electricity. Treat it as electr
by andrewla 2y ago
Except in extremely exceptional circumstances, it is not useful to try to reason about the behavior of electrons when looking at electricity. Treat it as electrical fields and you'll be fine. The fields represent reality at the non-quantum scale much better than attempts to model non-quantum reality.
As a notable example, macroscopically electricity is totally symmetric - positive current flows the same as negative current does. There are components that exhibit asymmetric behavior but they can be arbitrarily oriented so it doesn't really matter.
- michaelt 2y agoYou're broadly correct when it comes to designing practical circuits. But if your aim is to answer questions like "why do different colour LEDs need different resistors" or "what does it mean for something to be a semiconductor" pretty soon people will start talking about 'electrons' and 'holes' and 'band gaps' and 'depletion regions'.
- andrewla 2y agoIt is true that this is how we tend to discuss these things, but the important thing in practical circuits (even semiconductor circuits) is how they behave, not why they behave that way. Really there has been only limited success in discovering new semiconducting technologies motivated from first principles -- it's mostly intuition and dabbling and experimentation that has yielded the advancements. To some degree of course motivated by models of behavior, but it's very easy to ignore all the blind alleys that theory has led down. Mostly you're better off understanding that semiconductors work by "magic" and knowing what the response curves look like (or building mental approximations and heuristics) and otherwise just treating things in terms of currents and voltages (and fields at the lower level as necessary).