Physics 9702 · AS & A Level · Temperature scales

Temperature scales — practice question

At $0\,^{\circ}\text{C}$, the thermistor has a resistance of $3840\,\Omega$. When it is at $100\,^{\circ}\text{C}$, its resistance falls to $190\,\Omega$. If the thermistor is placed in water at one fixed temperature, the resistance is $2300\,\Omega$.
(a(i))[2]

Assuming that the resistance of the thermistor varies linearly with temperature, calculate the temperature of the water.

(a(ii))[3]

The water temperature, when read on the thermodynamic scale of temperature, is $286\,\text{K}$. Using the meaning of the thermodynamic scale of temperature, comment on your answer in (i).

(b)[4]

A polystyrene cup holds a mass of $95\,\text{g}$ of water at $28\,^{\circ}\text{C}$. An ice cube of mass $12\,\text{g}$ is added to the water. At the start, the ice is at $0\,^{\circ}\text{C}$. The water, with specific heat capacity $4.2 \times 10^{3}\,\text{J kg}^{-1}\text{K}^{-1}$, is stirred until all of the ice has melted. Assuming the cup has negligible mass and there is no heat transfer to the surroundings, calculate the final temperature of the water. The specific latent heat of fusion of ice is $3.3 \times 10^{5}\,\text{J kg}^{-1}$.

Worked solution & mark scheme

This 9-mark question has a full step-by-step worked solution and mark scheme. One marking point: Correct proportionality from the resistance-temperature scale

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