A magnet is pushed into a coil at the same speed on two occasions.
The first time, the ends of the coil are connected to a resistor. The second time, the ends of the coil are not connected to anything.
Why is a larger force needed to push the magnet in the first time?
A larger potential difference is induced, and this repels the magnet
No potential difference is induced when the ends of the coil are not joined
A current flows, and its magnetic field opposes the motion of the magnet
The resistor becomes magnetised and attracts the magnet back out of the coil
48 exam-style questions on OCR GCSE Physics 4.2 Uses of magnetism, covering 4.2.1 The motor effect, 4.2.2 Fleming's left-hand rule, 4.2.3 The force on a current-carrying conductor, 4.2.4 The electric motor, 4.2.5 Electromagnetic induction, 4.2.6 Alternators and dynamos, 4.2.7 How transformers work, 4.2.8 Transformer turns ratio, 4.2.9 Potential differences and turns in transformers, and 4.2.10 Microphones, loudspeakers and headphones. Each one has a worked solution and a mark scheme showing where the marks go.