September 20, 2008


Electric Current Flow
An electric current is the amount or number of electrons flowing through a conductor or a circuit from an area of negative charge to an area of positive charge. Electric current is represented by letter I when used in a circuit. Letter “I” means “intensity of current flow”. The basic unit used to measure the intensity of current flow is called ampere. It is named after Andre Marie Ampere. Ampere represents the amount of current in the conductor when one coulomb of charge moves past a point in one second. The relationship between amperes and coulomb per second can be expressed as:

I = Q/T
Where: I = current measured in amperes
Q = quantity of electrical charge in coulombs
T = time in seconds

1. What is the current in amperes if 27 coulombs of charge flow past a point in an electric circuit in 3 seconds?

I = ?
Q = 27 coulombs
t =FE4xeconds

I = Q/t
I = 27/3
I = 9 amperes

2. A circuit has a current of 2 amperes. How long will it take for one coulomb to pass a given point in the circuit?

I = 2 amperes
Q = 1 coulomb
t = ?

t = Q/I (derived from the formula I = Q/t)
t = 1/2
t = 0.5 seconds