(i) Explain why a transformer requires alternating current (a.c.) to operate. (ii) State two environmental disadvantages of generating electricity using fossil fuels.
A step-up transformer at a power station converts the generator output of 18 kV to a transmission voltage of 135 kV. The primary coil of the transformer has 600 turns. Calculate the number of turns on the secondary coil.
Explain the advantages of transmitting electrical energy at very high voltages such as 135 kV.
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.