An emergency relief worker uses a hand-cranked generator to charge a battery pack. Initially, when the battery is disconnected, the crank turns very easily at a constant speed. When the empty battery pack is connected to the generator and begins drawing current, the worker finds they must exert a significantly larger force to maintain the same constant rate of rotation.
Explain why it is more difficult to turn the crank when the generator is actively charging the battery.
4 exam-style questions on Edexcel GCSE Physics 13.1 Inducing a current, covering 13.1.1 Producing an electric current by induction, 13.1.2 Factors affecting the induced potential difference, 13.1.3 Alternators and dynamos, and 13.1.4 Microphones and loudspeakers. Each one has a worked solution and a mark scheme showing where the marks go.