(a)[4]
A coil of insulated wire is wound around a copper core, as shown in Fig. 10.1. An alternating current is passed through the coil. The heating effect of the current in the coil is negligible. Explain why the temperature of the core rises.
(b)
Two hollow tubes of equal length are suspended vertically, as shown in Fig. 10.2. One tube is plastic and the other is aluminium. Two small similar bar magnets A and B are held above the tubes and then released at the same time.