**The speed of electric current**
Since nothing visibly moves when the charge-sea flows, we cannot measure the speed of its flow by eye. Instead we do it by making some assumptions and doing a calculation. Let's say we have an electric current in normal lamp cord connected to bright light bulb. The electric current works out to be a flow of approximately 3 inches per hour. Very slow!

Here's how I worked out that value. I know:

Bulb power: about 100 watts, about 100V at 1A

Value for electric current: I = 1 ampere

Wire diameter: D = 2/10 cm, radius R=.1cm

Mobile electrons per cc (for copper, if 1 per atom): Q = 8.5*10^+22

Charge per electron: e = 1.6*10^-19

The equation:

cm/sec = ________I_______ = .0023 cm/sec = 8.4 cm/hour

................... Q * e * R^2 * pi

This is for DC. Chris R. points out that for a particular value of frequency of AC, the "skin effect" can cause the flow of charges in the center of a wire to be reduced while the current on the surface becomes stronger. There are fewer charges flowing, and hence they must flow faster. ("Skin Effect" is stronger at high frequencies and with thick wires. The effect can USUALLY be ignored in thin wires at 60Hz power-line frequencies.)

From:

http://amasci.com/miscon/speed.html
**It's more complicated than I thought.**