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P1.3.1 - AQA GCSE Physics Unit 1

 

 

P1.2.1

Energy transfers and efficiency

a) Examples of energy transfers that everyday electrical appliances are designed to bring about.

kWh calculations

 
b) The amount of energy an appliance transfers depends on how long the appliance is switched on and its power.

c) To calculate the amount of energy transferred from the mains using:

E = P x t

 

E is energy transferred in joules, J

P is power in watts, W

t is time in seconds, s

 

This equation may also be used when:

E is energy transferred in kilowatt-hours, kWh

P is power in kilowatts, kW

t is time in hours, h

Candidates will not be required to convert between kilowatt-hours and joules.

d) To calculate the cost of mains electricity given the cost per kilowatt-hour.