Figure 8.1 shows two parallel, oppositely charged metal plates. On Figure 8.1, draw four field lines to show the pattern and the direction of the electric field between the two parallel plates.

Draw with the mouse or a finger.

8(b)(i)Potential Dividers SensorsEasy1 mark

Figure 8.2 shows an electric circuit that includes a thermistor, component X and a relay. The relay operates a lamp. Identify component X.

Figure 8.2, a circuit with component X in series with a thermistor across a d.c. supply, feeding a relay coil whose switch closes a second circuit containing a lamp and a cell

8(b)(ii)Potential Dividers SensorsMedium3 marks

The temperature increases. The lamp lights. Complete the sentences to explain, in terms of potential difference (p.d.) and resistance, why the lamp lights.

When the temperature of the thermistor increases, the of the thermistor . This causes the p.d. across the to increase. The magnetic field produced by the relay coil . The relay coil attracts , which causes the lamp to light.

8(b)(iii)Current Potential DifferenceEasy2 marks

The current in the lamp is 3.2 A. Calculate the charge that flows through the lamp in 120 s.