Fig. 9.1 shows a simple relay used to switch a mains electric motor on and off. [Figure 9.1]

1. (a)(i)Explain why the motor switches on when switch S is closed.[3]
2. (a)(ii)Explain why the core is made of iron rather than steel.[2]
3. (a)(iii)A student suggests that the motor can be turned on and off without a relay. He suggests connecting the mains to a simple switch in series with the motor. Suggest one reason why, in some situations, using the relay is better.[1]
4. (b)(i)Fig. 9.2 shows the coil of wire wrapped around a cardboard tube. There is no core. There is an electric current in the wire in the direction shown by the arrows. [Figure 9.2] On Fig. 9.2, draw the pattern of the magnetic field inside and around the coil. Mark the direction of this magnetic field.[4]
5. (b)(ii)On Fig. 9.2, mark the N-pole of the coil.[1]
6. (c)(i)The supply of current to the coil is removed. The ends of the coil are connected to a sensitive ammeter, as shown in Fig. 9.3. [Figure 9.3] Describe how a permanent magnet is used to produce a large reading on the ammeter.[2]
7. (c)(ii)Explain why a current is produced in (i).[2]

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