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CAIE A-Level Physics A2 14.2 Temperature Scales Questions

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

Question 1

[Maximum number: 6]

Question (a)

(a)

State the magnitude and unit of absolute zero on the thermodynamic temperature scale.

[ 1 ]

Question (b)

(b)

Explain why temperature measured using a laboratory liquid-in-glass thermometer does not give a measurement of thermodynamic temperature.

[ 1 ]

Question (c)

(c)

Fig. 2.1 shows a simplified diagram of a type of thermometer called a platinum resistance thermometer.

Fig. 2.1

Fig. 2.1

The glass tube is immersed in the environment for which the temperature is to be determined. The resistance between the terminals X and Y is measured.

Fig. 2.2 shows the variation of the resistivity ρ\rho of platinum with thermodynamic temperature T.

Fig. 2.2

Fig. 2.2

[ 4 ]

Question (i)

(i)

Explain how Fig. 2.2 shows that platinum is a suitable metal for use in a resistance thermometer.

[ 2 ]

Question (ii)

(ii)

Suggest a reason why a platinum resistance thermometer is not suitable for measuring a rapidly changing temperature.

[ 1 ]

Question (iii)

(iii)

Suggest a type of thermometer that is suitable for measuring a rapidly changing temperature.

[ 1 ]

Question 2

[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 ]

Question 3

[Maximum number: 4]

Question (a)

(a)

Fig. 3.1 shows the variations with temperature of the densities of mercury and of water between 0∘C0^{\circ} \mathrm{C} and 100∘C100^{\circ} \mathrm{C}.

Fig. 3.1

Fig. 3.1

Temperature may be measured using the variation with temperature of the density of a liquid.
Suggest why, for measuring temperature over this temperature range:

[ 3 ]

Question (i)

(i)

mercury is a suitable liquid

[ 1 ]

Question (ii)

(ii)

water is not a suitable liquid.

[ 2 ]

Question (b)

(b)

A beaker contains a liquid of mass 120 g . The liquid is supplied with thermal energy at a rate of 810 W . The beaker has a mass of 42 g and a specific heat capacity of 0.84Jg−1 K−10.84 \mathrm{Jg}^{-1} \mathrm{~K}^{-1}. The beaker and the liquid are in thermal equilibrium with each other at all times and are insulated from the surroundings.

Fig. 3.2 shows the variation with time t of the temperature of the liquid.

Fig. 3.2

Fig. 3.2

[ 1 ]

Question (i)

(i)

State the boiling temperature, in ∘C{ }^{\circ} \mathrm{C}, of the liquid.

temperature =……… ∘C=\ldots \ldots \ldots ~{ }^{\circ} \mathrm{C}

[ 1 ]

Question 4

[Maximum number: 2]

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.

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

Question 5

[Maximum number: 1]

A beaker contains a liquid of mass 120 g . The liquid is supplied with thermal energy at a rate of 810 W . The beaker has a mass of 42 g and a specific heat capacity of 0.84Jg−1 K−10.84 \mathrm{Jg}^{-1} \mathrm{~K}^{-1}. The beaker and the liquid are in thermal equilibrium with each other at all times and are insulated from the surroundings.

Fig. 3.2 shows the variation with time t of the temperature of the liquid.

Fig. 3.2

Fig. 3.2

State the boiling temperature, in ∘C{ }^{\circ} \mathrm{C}, of the liquid.

temperature =……… ∘C=\ldots \ldots \ldots ~{ }^{\circ} \mathrm{C}

Question 6

[Maximum number: 1]

State the magnitude and unit of absolute zero on the thermodynamic temperature scale.

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