A-Level Physics: Thermal Physics and Ideal Gases

Thermal physics rewards disciplined bookkeeping: energies in joules, temperatures in kelvin, and a clear head about which gas law applies. This quiz enforces all three habits across the topic's examinable core.

The heat-energy questions work the two central quantities with real numbers: specific heat capacity recovered from an electrical heating experiment — power times time equated to mcΔθ, giving 800 J kg⁻¹ K⁻¹ — and specific latent heat of fusion from the energy needed to melt a given mass. These are exactly the shapes the required practicals produce.

The gas-law questions cover each law in its natural scenario: Boyle's law for an isothermal compression (pressure quadrupling as volume quarters), the pressure law for a rigid heated container, and Charles's law with the kelvin conversion made explicit — the 20 °C to 100 °C case where working in celsius is the classic error. The full ideal gas equation appears with moles and the gas constant, and a constant-pressure expansion brings in work done as pΔV.

The kinetic-theory questions handle the model itself: which assumptions (elastic collisions, negligible molecular volume) genuinely belong to the ideal-gas model, what internal energy is — the sum of random kinetic and potential energies of the molecules — and what absolute zero means as the floor of molecular kinetic energy.

Every question supplies its constants and values, in line with the exam's data booklet, and every explanation carries the kelvin conversions and unit checks in the working — because in thermal physics that is precisely where the marks are lost.

• Recover specific heat capacity and latent heat from experimental energy inputs
• Choose and apply the correct gas law for each constraint scenario
• Convert temperatures to kelvin before every gas-law substitution
• Apply pV = nRT and compute work done at constant pressure
• State the kinetic-theory assumptions and the meaning of internal energy and absolute zero

Topic scope follows the A-level physics content — as organised, for example, in section 3.6.2 (Thermal physics) of the AQA A-level Physics (7408) specification: thermal energy transfer, specific heat capacity and latent heat, the gas laws, the ideal gas equation and the kinetic theory model.