AQA paper 2: thermal physics, fields and nuclear physics · A-Level Physics · Courselo

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AQA paper 2: thermal physics, fields and nuclear physics

6 min readA-Level Physics

Paper 2 is 2 hours, 85 marks and 34% of the A-level, with the same layout as Paper 1: 60 marks of structured questions and 25 multiple-choice questions. The content is Year 13: section 6.2 (thermal physics), section 7 (gravitational and electric fields, capacitance, magnetic fields and electromagnetic induction) and section 8 (nuclear physics). Sections 1–6.1 are assumed knowledge, and the paper uses them constantly: circular motion inside orbits and cyclotrons, exponentials in capacitors and decay, momentum in kinetic theory. The target is 68/85 (80%). The notional A* in June 2026 was 64.

Timing plan

Elapsed	Target
0–2 min	Flick through. Find the 6-mark question and the longest calculation
45 min	About 30 of the 60 Section A marks attempted
87 min	Section A finished
117 min	All 25 MCQs done. Use the last 3 minutes on flagged items

Paper 2 calculations chain more steps than Paper 1 (an orbit question can need circular motion, gravitation and energy in one part), so protect the 87-minute checkpoint. If a part stalls, write the equations you would use, flag it and move on.

The recurring calculations

Topic	Core equations	The trap
Thermal energy	$Q = mc\Delta\theta$ , $Q = ml$ , $Pt = mc\Delta\theta$	Missing the phase-change stage when ice warms to water
Ideal gases	$pV = nRT = NkT$ , $\frac{1}{2}m(c_{\text{rms}})^2 = \frac{3}{2}kT$
Gravitational fields	$g = \frac{GM}{r^2}$ , $V = -\frac{GM}{r}$ , ,
Electric fields	$F = \frac{Q_1Q_2}{4\pi\varepsilon_0 r^2}$ , ,
Capacitors	$C = \frac{Q}{V}$ , $E = \frac{1}{2}QV$ , ,
Magnetic fields	$F = BIl$ , $F = BQv$ , $r = \frac{mv}{BQ}$
Induction and a.c.	$N\Phi = BAN\cos\theta$ , $\varepsilon = N\frac{\Delta\Phi}{\Delta t}$ , ,
Nuclear	$A = \lambda N$ , $N = N_0e^{-\lambda t}$ , ,

The explanations examiners reward

Written marks go to complete cause-and-effect chains. Learn these five until they are automatic.

Gas pressure rises with temperature (fixed volume). The molecules’ mean kinetic energy rises, so they move faster. Each collision with a wall gives a larger change of momentum, and collisions are more frequent, so the rate of change of momentum at the walls increases. By Newton’s second law the force increases, and pressure is force per unit area.
Lenz’s law in action. The magnet’s movement changes the flux linkage, which induces an emf and, in a complete circuit, a current. The current’s magnetic field opposes the change that caused it, so work must be done against it: that is where the electrical energy comes from.
Transformer losses. Eddy currents in the core are reduced by laminating it. Resistive heating in the coils is reduced by thick, low-resistance wire. Flux leakage is reduced by winding the coils on top of each other on a soft-iron core, and hysteresis loss by using a core that’s easy to magnetise and demagnetise.
Thermal fission reactor. The moderator slows fast neutrons by collisions until they are thermal, so they are more likely to cause fission in uranium-235. Control rods absorb neutrons so that, on average, exactly one neutron from each fission causes another fission. The coolant carries the thermal energy to the heat exchanger.
Why fission and fusion release energy. Both processes move nuclei towards iron-56 at the peak of the binding-energy-per-nucleon curve. The products are more tightly bound, and the increase in total binding energy is released, mostly as kinetic energy of the products.

Synoptic links to expect

Paper 2 context	Paper 1 physics it needs
Orbits and satellites	$F = \frac{mv^2}{r}$ , energy conservation
Charged particle in a magnetic field	Circular motion, momentum,

The geostationary orbit is a useful sanity check. A 24-hour period above the equator, moving in the direction of the Earth’s rotation, gives an orbital radius of about $4.2 \times 10^7$ m, roughly $3.6 \times 10^7$ m above the surface.

Multiple-choice patterns

Inverse-square fields. At three times the distance, the field strength is $\frac{1}{9}$ and the potential is $\frac{1}{3}$ .

Common mistakes

Quick recap

85 marks in 120 minutes: Section A done by 87 minutes, then 30 minutes for the MCQs.
Target 68/85. Expect Paper 1 physics inside most Paper 2 questions.
Drill the eight calculation families and their traps: kelvin, $r$ from the centre, prefixes, flux linkage, background.
Learn the five explanation chains word by word.