A 4.00 {rm A} current runs through a 12-gauge copper wire (diameter 2.05 {rm mm}) and through a light bulb. Copper has 8.5 times 10^{28} free electrons per cubic meter.
How many electrons pass through the light bulb each second?
What is the current density in the wire?
At what speed does a typical electron pass by any given point in the wire?
If you were to use wire of twice the diameter, which of the above answers would change? Would they increase or decrease?