Give the reason plastic behaves as an electrical insulator.
Explain why aluminium is not used to make the magnet.
Explain why iron is not used to make the magnet.
In one experiment, the magnet in Fig. 10.1 is moved leftwards so that it enters the solenoid. The N-pole of the magnet travels from Y to X at a constant speed. As it moves, the ammeter shows a small current. Explain why a current is produced in the solenoid while the magnet is moving.
The N-pole takes 0.14 s to move from Y to X. During this motion, the ammeter reads 0.045 mA. The resistance of the solenoid is $1.2\,\Omega$. Calculate the potential difference (p.d.) across the solenoid.
Calculate the charge that passes through the solenoid while the N-pole moves from Y to X.
In a second experiment, the N-pole moves faster than it did in the first experiment. It now takes only 0.070 s to travel from Y to X. The ammeter still shows a current in the same direction. State and explain how the size of this current compares with the size of the current in the first experiment.
Explain why the same amount of charge passes through the coil in both the first and second experiments.
State two ways in which the apparatus shown in Fig. 10.1 can be used to produce a current in the solenoid in the opposite direction.