1. The problem statement, all variables and given/known data: When a steady current flows through a conductor, the electrons in it move with a certain average 'drift speed'. The drift speed of electrons for a typical copper wire is about 1 mm s-1 . How is it then that an electric bulb lights up as soon as we turn the switch on? 2. Relevant equations: N/A 3. The attempt at a solution: It cannot be that a current starts only when an electron from one terminal of an electric supply physically reaches the other terminal through a bulb, because the drift speed of electrons in conducting wire is very slow. In my opinion, when an electron moves through a conductor with its drift velocity, it collides with other electrons in a conductor, as a result of which other electrons come in motion too the same way until they reach the output. Please rectify me if I am wrong or right.