# Alternating current

1. Apr 19, 2010

### ronaldoshaky

Hello

I read on Wikipedia that alternating current periodically changes direction. So if it keeps going backwards and then forwards how does the charge get around the circuit?

Thanks

2. Apr 19, 2010

### JDługosz

Think of beads on a wire, filling the wire like a pearl necklace. Suppose the wire forms a loop a meter in diameter.

Push a bead forward 3 cm. Pull it back 3 cm. Repeat. Your finger is the motive force. Have someone else watch, somewhere on the far side of the loop: he is the amp meter. Will he report beads moving? Yes, back and forth, at whatever velocity.

--John

3. Apr 19, 2010

### karkas

I would like to add something to your example JD, something that maybe even the initial poster knows already but I find that I should point out.

Direct current is unidirectional move of electric charge, but that doesn't mean that electrons travel from the switch to the electric device in order to power it. I think of the current as the "order" that is given to the wire by the generator for all free electrons along the wire to start moving, to one direction when it comes to direct current and back-forth when it comes to alternating current.

I hope I've helped.