An uncharged plastic rod is rubbed with an uncharged woollen cloth. As a result, the rod becomes negatively charged.

1. (a)Explain, in terms of particles, how the rod becomes charged and state what happens to the cloth.[2]
2. (b)Fig. 8.1 shows a metal sphere X on a plastic stand. [Figure 8.1] Explain why metals are electrical conductors and why plastics are electrical insulators.[2]
3. (c)(i)The negatively charged plastic rod is held above sphere X. Fig. 8.2 shows that it does not touch the sphere. [Figure 8.2] By drawing on Fig. 8.2, show the distribution of charge on X.[2]
4. (c)(ii)An earth wire is now connected to the metal sphere as shown in Fig. 8.3. [Figure 8.3] State what happens to the charges on the sphere as the earth wire is connected.[1]
5. (c)(iii)The earth wire in (ii) stays connected to the metal sphere. Describe the distribution of charge on the sphere.[2]
6. (c)(iv)The earth wire is disconnected from the sphere and then the negatively charged rod is moved away from the sphere. Explain what happens to the charges on the sphere as the charged rod is moved away.[2]
7. (d)(i)A second metal sphere Y is negatively charged. There is an electric field surrounding Y. State what is meant by 'electric field'.[1]
8. (d)(ii)Fig. 8.4 shows the negatively charged sphere Y. The negative charges are not shown. [Figure 8.4] On Fig. 8.4, draw the pattern and mark the direction of the electric field lines surrounding sphere Y.[3]

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