Physics-Electrical energy

Electrical energy

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Electrical energy

Electrical appliances

  • Electrical appliances can transfer electrical energy into useful energy at the flick of a switch
  • Uses of everyday electrical appliacnces include heating, lighting, making objects move and creating sound and visual images
  • An electrical appliance is designed for a particular purpose and should waste as little energy as possible
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Electrical energy

Electrical power

  • Power is rate of transfer of energy
  • P=E/t
  • Efficiency=useful power out/total power in (x100%)
  • P=power in watts, W
  • E is the energy in joules, J
  • t is the time taken (in seconds) for the energy to be transferred
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Electrical energy

Using electrical energy

  • The kilowatt-hour is the energy supplied to a 1kW appliance in 1 hour
  • E=P x t
  • Total cost= number of kWh x cost per kWh
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Electrical energy

Cost effectiveness matters

  • Cost effectiveness means getting the best value for money
  • To compare the cost effectiveness of different appliances, we nees to take account of a number of different costs
  • These may include:
  • The cost of buying the appliance 
  • The cost of installing the appliance
  • The running costs
  • The maintenance costs
  • Environmental costs
  • The interest charged in a loan to buy the appliance
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