A technician places a small loudspeaker beside a ventilation duct and uses it as a sound sensor. A steady tone makes the cone undergo 54 complete cycles in 0.12 s. The tone then continues unchanged for a further 8.0 s.
Calculate the number of times the induced potential difference changes direction during the 8.0 s interval.
92 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.