(a)[2]
State what Lenz’s law says.
(b)[4]
A metal ring is hung from a fixed point $P$ by a thread, as shown in Fig. 10.1. It is pulled a distance $d$ aside and then released. The ring makes many oscillations before it comes to rest. The poles of a magnet are then placed close to the ring so that the ring hangs halfway between the poles of the magnet, as shown in Fig. 10.2. The ring is again displaced by a distance $d$ and released. Explain why the ring makes fewer oscillations before coming to rest.
(c)[3]
The ring in (b) is now cut so that it has the shape shown in Fig. 10.3. Explain why, when the procedure in (b) is repeated, the cut ring makes more oscillations than the complete ring when oscillating between the poles of the magnet.