AQA GCSE Physics

Revision Notes

7.3.7 AC & High Voltage Transmission

Higher Tier Only

AC & High Voltage Transmission

  • Transformers have a number of roles:
    • They are used to increase the potential difference of electricity before it is transmitted across the national grid
    • They are used to lower the high voltage electricity used in power lines to the lower voltages used in houses
    • They are used in adapters to lower mains voltage to the lower voltages used by many electronic devices

Advantages of High Voltage Transmission

  • When electricity is transmitted over large distances, the current in the wires heats them, resulting in energy loss
  • To transmit the same amount of power as the input power the potential difference at which the electricity is transmitted should be increased
    • This will result in a smaller current being transmitted through the power lines
    • This is because P = IV, so if V increases, I must decrease to transmit the same power
  • A smaller current flowing through the power lines results in less heat being produced in the wire
    • This will reduce the energy loss in the power lines

power-lines, IGCSE & GCSE Physics revision notes

Electricity is transmitted at high voltage, reducing the current and hence power loss in the cables

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