A transformer consists of two coils of insulated wire wound on a magnetic core. State a suitable material for: (i) the coils, (ii) the core.
A lamp has a normal working voltage of 12 V12\text{ V}12 V. A transformer is used to enable this lamp to operate at normal brightness when connected to a 120 V120\text{ V}120 V mains supply. The primary coil of the transformer has 600600600 turns and is connected to the mains. Calculate the number of turns needed in the secondary coil.
A technician wants to use this transformer to light four identical 12 V12\text{ V}12 V lamps. (i) What would happen to the lamps if the technician connected them directly across the 120 V120\text{ V}120 V mains supply? (ii) Describe how the four lamps should be connected to the secondary terminals of the transformer so that they all light up at normal brightness.
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.