A transformer is to be used to provide a 12 V output from a 240 V supply.
What are suitable numbers of turns for the primary coil and for the secondary coil?
Primary turns = 100, Secondary turns = 2000
Primary turns = 400, Secondary turns = 80
Primary turns = 1200, Secondary turns = 60
Primary turns = 240, Secondary turns = 228
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.