Question

The electron drift speed in a metal wire is exceedingly slow. Yet, when you turnon the light switch the light begins to illuminate almost immediately. Explain whyt his is not a paradox?

Answer 1

Explanation:

The misunderstanding here is that the thing that turns on the light bulb is not the same electrons near the light switch. So, the electrons near the switch is not moving all the way across the circuit instantly. The electrons are distributed across the wire. When the light switch is turned on, the circuit is connected and there is a potential difference between the bulb and the source. This potential difference creates an electric field, and free electrons move under the influence of this electric field according to Coulomb's Law. When they start to move the electrons closest to the bulb causes the bulb to glow.

So, the important factor here is not the drift velocity of the electrons but the number of electrons and the strength of the electric field.