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LearnCambridge97022025–2027Paper 4 · A Level Structured QuestionsTemperature

Paper 4 · Module

Temperature

2 subtopics≈ 65 min in total

Start the module: Thermal equilibrium and temperature scales Open graphing calculator

Thermal equilibrium and temperature scales
Thermal energy flows from hotter to colder regions until they reach the same temperature: thermal equilibrium. Any property that changes with temperature (length of mercury, resistance, thermocouple e.m.f.) can make a thermometer, but different properties don't agree between fixed points. The thermodynamic scale doesn't depend on any substance: its zero is absolute zero, and $T/\text{K}=\theta/°\text{C}+273.15$ .
≈ 30 min
Specific heat capacity and latent heat
Specific heat capacity $c$ is the energy needed per unit mass per unit temperature rise: $Q=mc\Delta\theta$ . Water's $c$ is about $4200$ J kg⁻¹ K⁻¹. Specific latent heat $L$ is the energy needed per unit mass to change state at constant temperature: $Q=mL$ . Vaporisation needs much more energy than melting because molecules must be completely separated and push back the atmosphere.
≈ 35 min