4.2.1 Electrical Current

Electricity Comes Alive

Definitions• current: RATE OF CHARGE FLOW

• unit: C/s or AMPERE• requires:

• POTENTIAL DIFFERENCE• PATH FOR FLOW

tqI

• 100 coulombs of charge pass through point A in 4.0 seconds.– What is the rate of current flow through point A?

Example #1

I = Δq / t

I = 100 C / (4.00 s)

I = 25 A

A

• During a thunderstorm a lightning strike transfers 15.0 coulombs of charge in 10.0 milliseconds.– What was the electrical current produced in the strike?

Example #2

I = Δq / t

I = 15.0 C / (10 x 10-3 s)

I = 1.5 x 105 A

• A wire carries a current of 50 amperes.– How much charge flows through the wire in 10 seconds?– How many electrons pass through the wire in 10 seconds?

Example #3

I = Δq / t

50 A = q / (10 s)

q = 500 C3.125 x 1021 e

End of 4.2.1 - PRACTICE