AQA GCSE Physics

Revision Notes

2.3.2 Electrical Energy

Energy & Power

  • Everyday appliances transfer electrical energy from the mains to other forms of energy in the appliance
    • For example, in a heater, this will transfer an electrical energy store into a thermal energy store
  • The amount of energy an appliance transfers depends on:
    • How long the appliance is switched on for
    • The power of the appliance
  • A 1 kW iron uses the same amount of energy in 1 hour as a 2 kW iron would use in 30 minutes
  • A 100 W heater uses the same amount of energy in 30 hours as a 3000 W heater does in 1 hour

Exam Tip

Remember that kilo (k) means 1000, so 1 kW = 1000 W

Energy Transfers in Appliances

  • As electricity passes around a circuit, energy is transferred from the power source to the various components (which may then transfer energy to the surroundings)
    • As charge passes through the power supply it is given energy
    • As it passes through each component it loses some energy (transferring that energy to the component)

Current and energy, IGCSE & GCSE Physics revision notesThe current transfers electrical energy from the power source and to the components

 

  • Different domestic appliances transfer energy from batteries, such as a remote control
  • Most household appliances transfer energy from the AC mains
  • This can be to the kinetic energy of an electric motor. Motors are used in:
    • Vacuum cleaners – to create the suction to suck in dust and dirt off carpets
    • Washing machines – to rotate the drum to wash (or dry) clothes
    • Refrigerators – to compress the refrigerant chemical into a liquid to reduce the temperature
  • Or, in heating devices. Heating is used in:
    • Toasters – to toast bread
    • Kettles – to boil hot water
    • Radiators – hot water is pumped from the boiler so the radiator can heat up a room

Washing Machine & Toaster, downloadable IGCSE & GCSE Physics revision notes

Energy transfers for a washing machine and toaster

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Ashika graduated with a first-class Physics degree from Manchester University and, having worked as a software engineer, focused on Physics education, creating engaging content to help students across all levels. Now an experienced GCSE and A Level Physics and Maths tutor, Ashika helps to grow and improve our Physics resources.
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