Transformers (WJEC GCSE Physics): Revision Note

Transformers

• A transformer is a device used to change the value of an alternating voltage or current

• This is achieved using electromagnetic induction

Structure of a Transformer

• A basic transformer consists of:

  • A primary coil

  • A secondary coil

  • An iron core

• Iron is used as the core connecting the two coils because it is easily magnetised by the magnetic field generated from the current in the coils

A transformer consists of a primary coil and a secondary coil connected by an iron core

Electromagnetic Induction in a Transformer

• An alternating current is supplied to the primary coil

  • This produces a changing magnetic field around it

• The iron core is easily magnetised, so the changing magnetic field passes through it to the secondary coil

  • This changing field cuts through the secondary coil and induces an alternating voltage 

  • This generates an alternating current that flows into the completed circuit beyond

  • Its frequency is the same as that through the primary coil