A substation uses a step-down transformer to deliver electricity to a local community.
Explain the principle of operation of a simple iron-cored transformer.
The transformer steps the supply voltage down from 120 000 V120\,000\text{ V}120000 V to 15 000 V15\,000\text{ V}15000 V.
There are 500500500 turns on the secondary coil. Calculate the number of turns on the primary coil.
The electrical power delivered to the primary coil of the transformer is 48 MW48\text{ MW}48 MW. Calculate the current in the primary coil.
275 exam-style questions on CIE IGCSE Physics 4.5 Electromagnetic effects, covering 4.5.1a Electromagnetic induction, 4.5.1b Direction of an induced e.m.f., 4.5.2 The a.c. generator, 4.5.3a Magnetic effect of a current and its applications, 4.5.3b Strength and direction of the field around wires and solenoids, 4.5.4a Force on a current-carrying conductor, 4.5.4b Force on beams of charged particles, 4.5.5 The d.c. motor, 4.5.6a Construction and operation of a transformer, 4.5.6b Turns ratio and current in a transformer, and 4.5.6c High-voltage transmission of electricity. Each one has a worked solution and a mark scheme showing where the marks go.