I am self-studying electricity and magnetism, and I am confused about a point.
I have learnt that the drift speed of an electron is extremely small. However, according to Drude's model, the electron jumps around very fast and bounces against other particles in a conductor. I also read that this random movement happens even in the absence of electric field.
But how this is possible? Electrons should lose kinetic energy when bouncing off particles, and should become slower and slower. Maybe this process takes really long time and thus we can consider the slow down negligible?
But then what is making a lightbulb glow? I know it is heat generated by bouncing off particles. In my naive understanding, I thought this was dependent on the flow of electrons, but I am now doubting this since they are drifting really slowly. Is it the random scatter movement? That's also weird: if the electrons are scattered around even without a field, then the lightbulb should glow even without a voltage source, which doesn't happen.
So my questions:
Does the "scattering speed" of the electrons depends on the presence of an electric field?
What makes the lightbulb glow? Is it the electron slowly drifting? Is it the scatter speed increasing due to the electric field? Both?
What is really going on then?