Transformers (Edexcel GCSE Physics)

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Operation of a Transformer

Higher Tier Only

  • A transformer is a device used to change the value of an alternating potential difference or current
  • This is achieved using the generator effect

Structure of a Transformer

  • A basic transformer consists of:
    • A primary coil
    • A secondary coil
    • An iron core
  • Iron is used because it is easily magnetised

Transformer Diagram, downloadable AS & A Level Physics revision notes

Structure of a transformer

How a Transformer Works

  • An alternating current is supplied to the primary coil
  • The current is continually changing direction
    • This means it will produce a changing magnetic field around the primary coil

  • The iron core is easily magnetised, so the changing magnetic field passes through it
  • As a result, there is now a changing magnetic field inside the secondary coil
    • This changing field cuts through the secondary coil and induces a potential difference

  • As the magnetic field is continually changing the potential difference induced will be alternating
    • The alternating potential difference will have the same frequency as the alternating current supplied to the primary coil

  • If the secondary coil is part of a complete circuit it will cause an alternating current to flow

The Role of Transformers

Higher Tier Only

  • A transformer can change the size of an alternating voltage
  • They also have a number of other roles, such as:
    • To increase the potential difference of electricity before it is transmitted across the national grid
    • To lower the high voltage electricity used in power lines to the lower voltages used in houses
    • Used in adapters to lower mains voltage to the lower voltages used by many electronic devices

  • step-up transformer increases the potential difference of a power source.
    • A step-up transformer has more turns on the secondary coil than on the primary coil

  • step-down transformer decreases the potential difference of a power source
    • A step-down transformer has fewer turns on the secondary coil than on the primary coil

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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.