A museum exhibit contains a working dynamo with a rotating coil in a magnetic field. During maintenance, the split-ring commutator is replaced with two slip rings. The coil is connected through stationary brushes to a complete external circuit.
Why does the output current become alternating?
The slip rings make the coil cut the magnetic field at a constant rate, so the output current reverses every half-turn.
The slip rings keep each end of the coil on the same brush as the coil's potential difference reverses, so the output current reverses every half-turn.
The slip rings swap each end of the coil to the other brush every half-turn, so the output current reverses every half-turn.
The slip rings reverse the magnetic field around the coil every half-turn, so the output current reverses every half-turn.
96 exam-style questions on AQA GCSE Physics 7.3 Induced potential, transformers and the National Grid (HT only), covering 7.3.1 Induced potential (HT only), 7.3.2 Uses of the generator effect (HT only), 7.3.3 Microphones (HT only), and 7.3.4 Transformers (HT only). Each one has a worked solution and a mark scheme showing where the marks go.