(a(i))[2]
For one temperature, the thermistor has a resistance of $1200\,\Omega$. Calculate the potential difference (p.d.) across the $2000\,\Omega$ resistor at this temperature.
(a(ii))[2]
Explain why the p.d. across the $2000\,\Omega$ resistor becomes larger when the temperature rises.
(b)[2]
Describe what occurs inside the relay in Fig. 8.2 so that the lamp switches on OR describe how the circuit and transistor in Fig. 8.3 make the lamp switch on.