The wire used to wind a solenoid is covered in a thin layer of plastic. Which explains why the wire is covered?
The plastic stops the magnetic field leaving the sides of the solenoid
The plastic stops the current passing straight between touching turns
The plastic makes each turn of the solenoid produce a stronger field
The plastic stops the iron core being magnetised by the coil current
39 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.