AQA GCSE Electrical Power
Electrical Power
Electrical power is the rate of energy transfer.
There are different equations for working with electrical power
Example question
A 5W light bulb is switched on for 2 minutes, calculate the energy transferred.
Convert the 2 minutes into seconds. 2 minutes = 120 seconds
Energy = Power x time
Energy = 5W x 120 seconds
Energy = 600J
Example calculation
1. A mains kettle uses 2300W and 230V.
(a)Calculate the current that kettle uses for normal use.
P = V x I
I = P/V
I = 2300/230 = 10A
Example calculation
1. A tumble dryer has a current of 11A flowing and a resistance of 20 ohms. Calculate the power of the tumble dryer.
P = I2 x R
P = 112 x 20
P = 2420W
Practice Questions
1.An electric heater uses 12.9kJ of energy whilst switched onand has a power rating of 600W. Calculate how long the heater was switched on for.
2.A 3kW kettle draw a current of 12A from the mains supply. Calculate the potential difference of the mains supply
3.A dishwasher has a power rating of 1.2kW and a resistance of 40Ω. Calculate the current flowing through the dishwasher.