A cinema loudspeaker has a coil in the magnetic field of a permanent magnet. A cone is attached to the coil. The current in the coil repeatedly reverses direction.
Explain how the current produces pressure variations in the air, and state what happens to the force on the coil when the current reverses.
90 exam-style questions on AQA GCSE Physics 7.2 The motor effect, covering 7.2.1 Electromagnetism, 7.2.2 Fleming's left-hand rule (HT only), 7.2.3 Electric motors (HT only), and 7.2.4 Loudspeakers (HT only). Each one has a worked solution and a mark scheme showing where the marks go.