A transformer has two coils of insulated wire wound on an iron core.
Explain how an alternating current in the primary coil produces a potential difference across the secondary coil.
A student connects the primary coil to a battery and a switch. She connects a lamp to the secondary coil.
The lamp flashes on briefly when she closes the switch, and again when she opens it. At all other times the lamp is off.
Explain these observations.
Suggest why the coils are made of insulated wire.
48 exam-style questions on OCR GCSE Physics 4.2 Uses of magnetism, covering 4.2.1 The motor effect, 4.2.2 Fleming's left-hand rule, 4.2.3 The force on a current-carrying conductor, 4.2.4 The electric motor, 4.2.5 Electromagnetic induction, 4.2.6 Alternators and dynamos, 4.2.7 How transformers work, 4.2.8 Transformer turns ratio, 4.2.9 Potential differences and turns in transformers, and 4.2.10 Microphones, loudspeakers and headphones. Each one has a worked solution and a mark scheme showing where the marks go.