Transformers (Cambridge International IGCSE Science)

Structure of a transformer

Extended tier only

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

  • This is achieved using the generator effect

• A basic transformer consists of:

  • a primary coil
  • a secondary coil
  • a soft iron core

• Iron is used because it is easily magnetised

Construction of a simple transformer

A simple transformer is made up of a primary coil and a secondary coil wound on a soft iron core

Step-up & step-down transformers

Extended tier only

• A transformer consists of a primary and secondary coil

  • The primary coil is the first coil
  • The secondary coil is the second coil

Step-up transformer

• A step-up transformer:

  • increases the voltage of a power source (V_ s greater than V_ p)
  • has more turns on the secondary coil than on the primary coil (N_ s greater than N_ p)

A step-up transformer has more turns on the secondary coil which increases the size of the voltage

Step-down transformer

• A step-down transformer:

  • decreases the voltage of a power source (V_ s less than V_ p)
  • has fewer turns on the secondary coil than on the primary coil (N_ s less than N_ p)

A step-up transformer has fewer turns on the secondary coil which decreases the size of the voltage