A student turns the handle of a simple alternating current (a.c.) generator, causing a rectangular coil to rotate between the north and south poles of a permanent magnet.
Explain, in terms of magnetic fields, how the rotation of the coil produces an alternating electromotive force (e.m.f.) across its output terminals.
State the position of the rotating coil relative to the magnetic field when the magnitude of the alternating output voltage is zero, and explain why the voltage is zero at this position.
A heating resistor and a switch are connected in series across the generator's output terminals. When the switch is closed, a current flows through the circuit. To keep the coil rotating at the same constant speed, the student must exert a significantly larger turning force on the handle.
Explain why a larger turning force is needed when the switch is closed.
24 exam-style questions on CIE IGCSE Physics 4.5.2 The a.c. generator. Each one has a worked solution and a mark scheme showing where the marks go.