Question

Current in a wire is due to the flow of electrons in the wire. Although the drift speeds of electrons in the wire is small, yet an electrical bulb lights up as soon as the switch is on . Explain Why many

Answer 1

The circuit has almost zero capacitance then the voltage applied on the switch reachs the load at almost the light speed then the power is applied that fast, the only delay noted is heating the filament or getting through the ballast. The drift speed is slow but the wire is already full of free electrons which moves almost simultaneously, the ones at switch will take long time (in DC) for making the whole trip, if ever.

Answer 2

The drift speed is slow but the wire is full of electrons hence when the switch is turned on the electrons start to move at the speed of light and hence the bulb turns on