AQA GCSE Electrical Power

AQA GCSE Electrical Power

Electrical Power

Electrical power is the rate of energy transfer. 

There are different equations for working with electrical power

 

Equation that links power, energy and time

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

Formula for calculating power using potential difference and current, including the triangle

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

power current and resistance equation for heating effect

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.

Accordion Content
Accordion Content
Accordion Content
Accordion Content