A laptop charger is connected to a 230 V a.c. mains electrical supply.
The plug of the charger contains a safety fuse. State and explain which of the three wires (live, neutral, or earth) must contain the fuse.
Inside the power adapter, a transformer is used to reduce the voltage from 230 V a.c. to 23 V a.c.
State the name of this type of transformer.
Describe the construction of this transformer, including details of the relative number of turns on each 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.