A student connects a thermistor in series with a battery and an ammeter. He uses the resistance of the thermistor to determine temperature.

1. (a)In the space below, draw a circuit diagram showing the thermistor, the battery and the ammeter.[3]
2. (b)(i)1.The student places the thermistor in a water bath at various temperatures and records the reading on the ammeter. Fig. 11.1 shows how the current varies with temperature. [Figure 11.1] The potential difference (p.d.) across the thermistor remains constant. The resistance of the thermistor is 240 Ω at a temperature of 20 °C. Using Fig. 11.1, calculate the potential difference (p.d.) across the thermistor,[3]
3. (b)(i)2.the resistance of the thermistor at a temperature of 40 °C.[2]
4. (b)(ii)The resistance of the thermistor is 240 Ω at a temperature of 20 °C and 48 Ω at a temperature of 60 °C. The resistance of the thermistor does not change linearly with temperature. Describe how the resistances at 20 °C, 40 °C and 60 °C show this is true.[2]
5. (c)(i)A thermocouple thermometer is another type of thermometer. Describe the structure of a thermocouple thermometer. You may draw a diagram if you wish.[3]
6. (c)(ii)State two advantages of a thermocouple thermometer over a liquid-in-glass thermometer. 1. 2.[2]

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