A rotation sensor contains a permanent magnet attached to a wheel and a fixed coil connected to a sensitive voltmeter. As the wheel rotates, the magnet passes close to the coil and the voltmeter briefly gives a reading.
Which statement explains why?
The passing magnet transfers electric charge to the coil, so a potential difference is produced.
The fixed number of turns in the coil produces a potential difference whenever the wheel rotates.
The strong magnetic field through the coil is enough to produce a potential difference on its own.
The passing magnet changes the magnetic field through the coil, so a potential difference is induced.
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.