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CAIE A-Level Physics 14.2 Temperature Scales

Practise using thermometric properties and calibration, explaining the thermodynamic scale and absolute zero, and converting kelvin and Celsius.

Syllabus
2028–2030
Course
Physics 9702
Level
A2

Exam points

  • use temperature-dependent physical properties to measure temperature and explain calibration
  • explain the substance-independent thermodynamic scale and identify absolute zero
  • convert between kelvin and Celsius accurately using the defined relationship

Covered syllabus points

14.2.1—A physical property that varies with temperature may be used for the14.2.2—The scale of thermodynamic temperature does not depend on the property of14.2.3—Convert temperatures between kelvin and degrees Celsius and recall that T /14.2.4—The lowest possible temperature is zero kelvin on the thermodynamic

14.2 Temperature scales question 1

[Maximum number: 5]

Fig. 2.1 shows a laboratory thermometer that is calibrated to measure temperature in degrees Celsius.

Fig. 2.1

Fig. 2.1

The thermometer makes use of the fact that the density of mercury varies with temperature.

Question (a)

(a)

State two other physical properties of materials, apart from the density of a liquid, that can be used for measuring temperature.

1

2

[ 2 ]

Question (b)

(b)

The thermometer is initially at 23.0∘C23.0^{\circ} \mathrm{C}, as shown in Fig. 2.1. It is used to measure the temperature of an insulated beaker of water that is at 37.4∘C37.4^{\circ} \mathrm{C}. The bulb of the thermometer is inserted into the water, and the water is stirred until the reading on the thermometer becomes steady.

The mass of water in the beaker is 18.7 g .
The mass of mercury in the thermometer is 6.94 g .
The specific heat capacity of water is 4.18 J g−1 K−14.18 \mathrm{~J} \mathrm{~g}^{-1} \mathrm{~K}^{-1}.
The specific heat capacity of mercury is 0.140 J g−1 K−10.140 \mathrm{~J} \mathrm{~g}^{-1} \mathrm{~K}^{-1}.
The glass of the thermometer and the beaker containing the water can be considered to have negligible heat capacity.

[ 1 ]

Question (i)

(i)

Suggest one change that could be made to the design of the thermometer that would enable it to give a more accurate measurement of temperature.

[ 1 ]

Question (c)

(c)

Explain why the thermometer in Fig. 2.1 does not provide a direct measurement of thermodynamic temperature.

[ 2 ]

14.2 Temperature scales question 2

[Maximum number: 1]

State the temperature, in degrees Celsius, of absolute zero.

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