A linear electromagnetic actuator opens a camera shutter. A straight section of conductor in the actuator is at right angles to a magnetic field. The force on the conductor initially moves the shutter open.
The current is reversed but remains the same size. The magnetic field is then adjusted, with no change to the conductor. The force still moves the shutter open and has the same size as before. What happens to the magnetic field?
It reverses direction and becomes weaker
It remains in the same direction and becomes stronger
It reverses direction and remains the same strength
It remains in the same direction and at the same strength
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.