(a)[1]
State the name of the metal that the electromagnet core is made from.
(b(i))[2]
The electromagnet is supplied by a 220 V d.c. source. The electromagnet is switched on and the current in the circuit is 39 A. Calculate the power transferred to the electromagnet.
(b(ii))[3]
The d.c. supply consists of batteries. They keep the magnet running for 4.5 hours before replacement is needed. Calculate the charge driven around the complete circuit in this time.
(c)[1]
When the electromagnet is first switched on on a very cold morning, the current is above 39 A before it drops to the normal value. Explain why the current is initially greater than 39 A.