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Electromagnetic induction

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Question 5

An electricity substation on the national grid uses a step-up transformer to prepare power for long-distance transmission.

a.

The number of turns on the primary coil of a step-up transformer is:

  • A the same as the number of secondary turns
  • B more than the number of secondary turns
  • C less than the number of secondary turns
  • D zero
[1]
b.

This transformer is designed to increase the voltage from 11 kV11\text{ kV}11 kV to 132 kV132\text{ kV}132 kV.

The primary current is 600 A600\text{ A}600 A.

(i) State the equation linking primary voltage, primary current, secondary voltage, and secondary current for a transformer.

(ii) Calculate the secondary current, assuming that the transformer is 100%100\%100% efficient.

[4]
c.

An engineer notes that the substation transformer's cooling system dissipates significant heat when operating under load. Suggest how this energy loss affects the electrical power output of the transformer compared to its power input.

[2]

Electromagnetic induction Questions

  1. IGCSE
  2. /Physics
  3. /Electromagnetic induction