Electric Current - Examples

Electric Current
































A typical automobile storage battery can deliver 60 amperes of current for about one hour. How much electric charge can it deliver?

Charge = (60C/s)(3600s) = 216,000C

Examples --- What this is an example of




































Consider 63 grams of copper.
Enough for a few dozen feet of wire (depending on the diameter), it contains copper atoms.

That makes moveable electrons.

The total moveable charge is about 100,000 coulombs.

Examples --- What this is an example of




































Calculate the average speed with which electrons move through a 1mm diameter wire carrying a ten amp current.

If the wire is ten meters long, then it contains about 63 grams of copper and thus has about 100,000C of moveable charge in it. If the wire carries a 10 amp current, then 10C of charge leaves one end of it each second. The time for all of the charge in the wire to leave is the time for an electron to travel the length of the wire. To exhaust 100,000C at 10C/s takes 10,000s, so the electrons travel 10m in 10,000s for an average velocity of 0.001m/s or 1mm/s.

Examples --- What this is an example of



































In a telephone or a telegraph, changes in the potential difference between two wires at one end of the line is transmitted to the other end at the speed of light.

Examples --- What this is an example of



































Return