A 60W light bulb is connected to a 120V outlet. How long in seconds does it take for 1 billion (109) electrons to pass through the light bulb?

Answer 1

The current will be
I = P/V = 60/120 = 0.5 A
which is 0.5 Coulombs per second.

10^9 electrons will pass through in time t such that
(0.5 C/s)* t = 10^9(electrons)*1.6*10^-19 (C/electron)

t = 3.2*10^-10 s