Question

When you flip a switch to turn on a light, the delay before the light turns on is determined by

• A. the speed of the electric field moving in the wire
• B. the drift speed of the electrons in the wire
• C. the number of electron collisions per second in the wire
• D. none of the above, since the light comes on instantly

Hint:

Remember that the delay in turning on the light is due to the propagation of the electric field, not the movement of electrons.

Answer 1

The Correct Option is A

When the switch is flipped, the electric field propagates at nearly the speed of light, which causes the light to turn on almost instantly. The drift speed of electrons is much slower and does not determine the delay.