AC & High Voltage Transmission (AQA GCSE Physics): Revision Note

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

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