In a small loudspeaker, a coil of wire is positioned within a radial magnetic field.
When a current of 25 mA25\text{ m{A}}25 mA passes through the coil, the magnetic force acting on the coil is 0.018 N0.018\text{ N}0.018 N.
The total length of the wire that forms the coil is 4.8 m4.8\text{ m}4.8 m.
Calculate the magnetic flux density around the coil, providing your answer to 2 significant figures.
13 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.