(a) A plotting compass contains a needle. The needle is a small magnet that can rotate about its centre. Fig. 7.1 shows the plotting compass placed close to a bar magnet. [Figure 7.1] (not to scale)

1. (a)(i)On Fig. 7.1 mark the magnetic poles on the bar magnet.[1]
2. (a)(ii)There is a piece of paper underneath the magnet. Describe how the compass is used to plot the magnetic field line that passes from one pole to the other and through P.[3]
3. (a)(iii)Describe how to use the compass in Fig. 7.1 to determine the direction of the magnetic field at P.[1]
4. (b)(i)Fig. 7.2 shows the apparatus a student uses to produce an alternating current (a.c.). [Figure 7.2] The magnet is moved into and out of the coil. Explain why a current is produced when the magnet moves.[2]
5. (b)(ii)Describe the movement of the magnet that produces an a.c. of frequency 0.50 Hz.[1]
6. (b)(iii)Describe how the centre-zero ammeter shows the current is a.c. rather than d.c. (direct current).[1]
7. (b)(iv)Explain why increasing the frequency of the a.c. produced also increases the magnitude (size) of the a.c produced.[1]

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