Energy transfers in everyday appliances

• Everyday electrical appliances are designed to bring about energy transfers
• The amount of energy an appliance transfers depends on:

  • how long the appliance is switched on for
  • the power of the appliance
• How different domestic appliances transfer energy from batteries or ac mains to the kinetic energy of electric motors or the energy of heating devices

  • Kettle - kettles transfer energy electrically from the mains ac supply to the thermal energy store of the heating element inside the kettle
  • Fan - energy is transferred electrically from the battery of a handheld fan to the kinetic energy store of the fan's motor
• Work is done when charge flows in a circuit
• Equation linked to energy transferred, power and time:

  energy transferred = power x time

  energy transferred in joules, power in watts, time in seconds
• Equation linked to energy transferred, charge flow and potential difference:

  • energy transferred = charge flow x potential difference

  energy transferred in joules, charge flow in coulombs and potential difference in volts
• Appliances with higher power ratings will consume more energy and produce a greater change in stored energy when in use than appliances with lower power ratings.