The National Grid (Edexcel GCSE Physics)

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High Voltage Transmission

  • When electricity is transmitted over large distances, the current in the wires heats them, resulting in energy loss
    • The electrical energy is transferred at high voltages from power stations
    • It is then transferred at lower voltages in each locality for domestic uses

  • 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 and improves the efficiency of the energy transfer

Power Loss National Grid, downloadable AS & A Level Physics revision notes

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

Stepping Up & Down

  • 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

  • For the transmission of electricity in the national grid to be at high voltages, the voltage must be stepped up by a step-up transformer
    • These are placed after the power station

  • For the domestic use of electricity, the voltage must be much lower
  • This is done by stepping down by the voltage using a step-down transformer
    • These are placed before buildings

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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Ashika

Author: Ashika

Expertise: Physics Project Lead

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.