The Transformer Equation (Edexcel GCSE Physics)

Higher Tier Only

• The output potential difference (voltage) of a transformer depends on:
  • The number of turns on the primary and secondary coils
  • The input potential difference (voltage)

• It can be calculated using the equation:

• This equation can be written using symbols as follows:

• Where:
  • V_p = potential difference (voltage) across the primary coil in volts (V)
  • V_s = potential difference (voltage) across the secondary coil in volts (V)
  • n_p = number of turns on the primary coil
  • n_s = number of turns on the secondary coil

• The equation above can be flipped upside down to give:

• The equations above show that:
  • The ratio of the potential differences across the primary and secondary coils of a transformer is equal to the ratio of the number of turns on each coil