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Electromagnets and transformers - AQADesign and use of transformers - Higher

Electromagnetism is due to the magnetic fields around electric currents. The fields can cause forces with other nearby magnets which can be used to make motors spin.

Part of Combined ScienceMagnetism and electromagnetism

Design and use of transformers - Higher

A is a device that can change the or of an alternating current:

  • a step-up transformer increases the voltage
  • a step-down transformer reduces the voltage

Design and use of transformers

A basic transformer is made from two coils of wire, a primary coil from the alternating current (ac) input and a secondary coil leading to the ac output. The coils are not electrically connected. Instead, they are wound around an iron core. This is easily magnetised and can carry from the primary coil to the secondary coil.

An iron core transformer, with the primary coil on the left hand side and secondary coil on the right hand side.
Figure caption,
Components of a transformer

When a transformer is working:

  1. A primary voltage drives an through the primary coil.
  2. The primary coil current produces a magnetic field, which changes as the current changes.
  3. The iron core increases the strength of the magnetic field.
  4. The changing magnetic field induces a changing potential difference in the secondary coil.
  5. The induced potential difference produces an alternating current in the external circuit.