What is the function of the split-ring commutator in a simple direct current (d.c.) generator?
to reverse the direction of the induced current inside the rotating coil every half-turn
to ensure that the current in the external circuit flows in one direction only
to allow the generator to be driven by an alternating current source
to minimize the electrical resistance of the rotating coil
35 exam-style questions on CIE IGCSE Physics 4.5.1a Electromagnetic induction. Each one has a worked solution and a mark scheme showing where the marks go.