An LED (bulb) lights up when it is in a closed circuit with a battery. ‘Because electrons flow in the circuit’. But what is the mechanism that transforms this kinetic energy of electrons into light energy? Should I be asking a different question?
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I don’t want to overcomplicate this excellent conversation with such a small point, however, I must. The electrons barely move at all. I’m sorry, but it’s the truth. They flow at the pace of millimeters per HOUR. The electric and magnetic fields are perturbated by the motion of the electrons, and it is the energy in these fields which get to act on the LED. I have absolutely no idea how to explain field theory simply. In fact, I doubt I could give it a proper detailed explanation. All that said, however, the view of the electrons themselves as being the holders and depositors of the energy is ultimately a completely valid mathematical viewpoint, with a few caveats/extra rules it’s just a different perspective.
Also, the wires. Wires have resistance, capacitance, and indutance. Taken together we call these things that the wires have the impedence of the wire. For wires that aren’t miles long it’s so small that we just pretend it’s zero and nothing is noticably different. Unless you’re making something very small like the insides of a computer’s CPU, in which case the electrical properties of your tiny metal “wires” suddenly become of extreme importance…
Should you be asking a different question? No, it’s an excellent question that could lead you down a dozen interesting fields of study.
As for how (or rather, why) this energy getting to an LED creates light, I’m glad someone else typed that up so well already.
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