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8.4.2 Types of Transformer

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There are 2 types of transformer, namely

  1. the step up transformer
  2. the step down transformer

Step-up Transformer

  1. A step-up transformer is one where the e.m.f. in the secondary coil is greater than the e.m.f. in the primary coil. It is used to increases the potential difference.
  2. The number of windings in the secondary winding is greater than the number of windings in the primary coil.
  3. The current in the primary coil is greater than the current in the secondary coil.

Step-down Transformer

  1. Conversely, a step-down transformer is one where the e.m.f. in the secondary coil is less than the e.m.f. in the primary coil. It is used to reduce the potential difference.
  2. The number of windings in the primary winding is greater than the number of windings in the secondary coil. 
  3. The current in the primary coil is lesser than the current in the secondary coil.

Calculation of Potential Difference Change


Vp = input (primary) potential difference
Vs = output (secondary) potential difference
Ip = input (primary) current
Is = output (secondary) current