The battery of a shake-to-charge emergency flashlight is recharged by a simple induction generator. In this generator, a permanent magnet slides back and forth through the center of a stationary coil of wire. Which statement is correct?
The induced electromotive force (e.m.f.) increases if the number of turns in the coil is decreased.
The induced e.m.f. increases if the magnet is shaken more rapidly back and forth.
The induced e.m.f. decreases if a stronger magnet of the same dimensions is used.
The induced e.m.f. is completely independent of the magnetic field strength of the magnet.
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.