Jewel, You're of course correct, there is voltage at the light socket even when there is nothing in said socket, but there is no current flow until you, or a less intelligent consumer, sticks something in the socket.
It's, as max says so well, the difference between voltage and current. There is a tendency to refer to electrical current as a a generic for voltage which it isn't.Saying "is ther current present' is not correct, there can be voltage present, but no current flowing. I'm sure we all get it, but its better to keep terms straight. Tom Fowle
