The National Grid (AQA GCSE Physics)

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The National Grid

  • The National Grid distributes electricity across the UK
    • It consists of a system of cables and transformers linking power stations to consumers (houses, factories and buildings)

  • Electrical power is transferred from power stations to consumers using the National Grid
  • The transformers include:
    • Step-up transformers which increase the voltage (and reduces the current) through the wires
    • Step-down transformers which decrease the voltage (and increases the current) through the wires

power-lines, IGCSE & GCSE Physics revision notes

The national grid

Benefits of The National Grid

  • The National Grid system is an efficient way to transfer energy due to the use of step-up and step-down transformers
  • The current generated by power stations is greater than that which is required for homes and other buildings, and so it must be transmitted through a network of wires that travel across the country
  • When electricity is transmitted over large distances, the resistance in the wires causes heating, which results in wasted energy transfers
  • By increasing the potential difference at which the current is transmitted, the same amount of power can be transferred using a much smaller current (due to the equation P = IV)
    • This results in less heating in the wire and hence less wasted energy

  • Therefore:
    • High potential difference means low current (less energy dissipated) for the same power
    • Low potential difference means high current (more energy dissipated) for the same power

  • The potential difference is increased using the step-up transformers and decreased using the step-down transformers

Worked example

The diagram shows part of the National Grid.power-lines, IGCSE & GCSE Physics revision notesExplain how the step-up transformer increases the efficiency of the National Grid.

    • The lower the current, the less heating due to resistance there will be in the wires 
    • From the diagram, the step-up transformer increases the voltage and decreases the current in the cables
    • By decreasing the current, the energy dissipated to the thermal store of the surroundings through the power cables is reduced
    • Therefore, there is more energy being transferred to homes which increases the efficiency of the National Grid

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

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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.