A water-flow sensor contains a turbine inside a pipe. A small permanent magnet is fixed to the edge of the turbine. During each revolution, the magnet moves towards and then away from a stationary coil outside the pipe. The coil is connected in a complete circuit to a data logger.
The turbine initially makes 5.0 rotations each second.
Explain why the data logger records a current that repeatedly changes direction while the turbine rotates.
The water flow increases, causing the turbine to make 8.0 rotations each second. The resistance of the circuit is unchanged.
Explain how the output recorded by the data logger changes.
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.