A light bulb is rated at 30 w when operated at 120 v. how much charge enters (and leaves) the light bulb in 1.0 min?

Power in a circuit = V. I

30 = (120) (I)

I = 0.25 A

We know, current is the rate of flow of charge per unit time. This means 0.25 A corresponds to the flow of 0.25 C of charge every second.

That implies, in a minute 0.25 x 60 = 15 C of charge flows.