In a simple direct-current (DC) motor, a split-ring commutator is used. Which statement correctly describes how the split-ring commutator enables the coil to rotate continuously in one direction?
It reverses the direction of the magnetic field every half turn of the coil.
It reverses the direction of the current in the coil every half turn of the coil.
It maintains a constant current direction relative to the coil at all times.
It increases the voltage supplied to the coil as it passes the horizontal position.
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.