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Effective revision for AQA A-Level Physics requires a clear understanding of the specification structure, which topics appear on which papers, the most commonly examined areas, and how topics link together. This lesson provides a complete specification map, a detailed overview of the most popular option (Astrophysics), the full list of equations to memorise, and a structured revision strategy.
The AQA A-Level Physics specification (7408) is organised into sections 3.1 to 3.12. Here is the complete map:
| Section | Topic | Key subtopics |
|---|---|---|
| 3.1 | Measurements and their errors | SI units, estimation, uncertainties, significant figures |
| 3.2 | Particles and radiation | Atomic structure, Standard Model, photoelectric effect, energy levels, wave-particle duality |
| 3.3 | Waves | Progressive and stationary waves, refraction, diffraction, interference, polarisation |
| 3.4 | Mechanics and materials | SUVAT, forces, Newton's laws, momentum, energy, work, power, materials, Young modulus |
| 3.5 | Electricity | Charge, current, pd, resistance, Ohm's law, resistivity, circuits, EMF, internal resistance, potential dividers |
| Section | Topic | Key subtopics |
|---|---|---|
| 3.6 | Further mechanics and thermal physics | 3.6.1 Periodic motion (circular motion, SHM, forced vibrations, resonance) — on Paper 1; 3.6.2 Thermal physics (internal energy, specific heat, ideal gases, molecular kinetic theory) — on Paper 2 |
| 3.7 | Fields and their consequences | Gravitational fields, Newton's law, orbits; Electric fields, Coulomb's law; Capacitance, charge/discharge; Magnetic fields, electromagnetic induction |
| 3.8 | Nuclear physics | Radioactivity, alpha/beta/gamma, nuclear radius, mass-energy, binding energy, fission, fusion |
| Section | Option | Key subtopics |
|---|---|---|
| 3.9 | Astrophysics | Telescopes, classification of stars, HR diagram, stellar evolution, cosmology, Hubble's law |
| 3.10 | Medical physics | X-rays, CT scans, gamma camera, PET scanning, ultrasound, MRI, radiation dosimetry |
| 3.11 | Engineering physics | Rotational dynamics, thermodynamics, heat engines |
| 3.12 | Turning points in physics | Electron discovery, photoelectric effect, wave-particle duality, special relativity |
| 3.13 | Electronics | Digital electronics, operational amplifiers, communication systems |
flowchart TD
A["AQA A-Level Physics"] --> B["Paper 1 (34%)"]
A --> C["Paper 2 (34%)"]
A --> D["Paper 3 (32%)"]
B --> B1["3.1 Measurements"]
B --> B2["3.2 Particles & Radiation"]
B --> B3["3.3 Waves"]
B --> B4["3.4 Mechanics & Materials"]
B --> B5["3.5 Electricity"]
B --> B6["3.6.1 Periodic Motion<br/>(Circular + SHM)"]
C --> C1["3.6.2 Thermal Physics"]
C --> C2["3.7 Fields<br/>(Gravitational, Electric,<br/>Capacitance, Magnetic)"]
C --> C3["3.8 Nuclear Physics"]
D --> D1["Section A: Practical Skills<br/>& Data Analysis (45 marks)"]
D --> D2["Section B: Optional Topic<br/>(35 marks)"]
Exam Tip: Section 3.1 (Measurements and their errors) is not tested as a standalone section — instead, it is embedded throughout all three papers. Questions on uncertainties, significant figures, and estimation can appear anywhere.
Astrophysics is by far the most popular optional topic. Here is a detailed overview of the content.
| Type | Principle | Advantages | Limitations |
|---|---|---|---|
| Refracting | Uses converging lenses; objective lens + eyepiece lens | Simple design | Chromatic aberration, heavy large lenses, difficult to support |
| Reflecting (Cassegrain) | Uses concave primary mirror + convex secondary mirror | No chromatic aberration, mirrors can be large, lighter | Alignment issues, secondary mirror blocks some light |
| Single-dish radio | Large parabolic dish collects radio waves | Detects radio sources invisible to optical, works in clouds/daylight | Low resolving power (long wavelengths), very large dishes needed |
| Radio interferometer | Array of dishes acting as one large telescope | Very high resolving power (effective diameter = array baseline) | Complex data processing, expensive |
| Quantity | Equation |
|---|---|
| Magnification (in normal adjustment) | M = f_objective / f_eyepiece |
| Minimum angular resolution (Rayleigh criterion) | theta ≈ lambda / D |
| Collecting power | Proportional to diameter² (area of aperture) |
Stars are classified by their spectra, which depends on surface temperature:
| Spectral Class | Colour | Surface Temperature (K) | Key Features |
|---|---|---|---|
| O | Blue | > 25,000 | He II lines, ionised metals |
| B | Blue-white | 10,000-25,000 | He I lines, neutral helium |
| A | White | 7,500-10,000 | Strong hydrogen Balmer lines |
| F | Yellow-white | 6,000-7,500 | Ca II lines, weaker H lines |
| G | Yellow | 5,200-6,000 | Strong Ca II, metal lines (Sun is G2) |
| K | Orange | 3,700-5,200 | Strong metal lines, TiO bands begin |
| M | Red | 2,400-3,700 | Strong TiO molecular bands |
Mnemonic: Oh Be A Fine Girl/Guy, Kiss Me
The luminosity (total power output) of a star is given by:
L = 4pi sigma r² T⁴
where sigma is the Stefan-Boltzmann constant (5.67 x 10⁻⁸ W m⁻² K⁻⁴), r is the stellar radius, and T is the surface temperature.
lambda_max T = 2.898 x 10⁻³ m K
This relates the peak wavelength of emission to the surface temperature. Hotter stars have shorter peak wavelengths (bluer).
The HR diagram plots luminosity (or absolute magnitude) against spectral class (or surface temperature).
Key regions:
| Region | Position on HR diagram | Stars |
|---|---|---|
| Main sequence | Diagonal band from top-left (hot, luminous) to bottom-right (cool, faint) | Majority of stars (including the Sun) |
| Red giants | Upper right (cool but luminous) | Stars that have exhausted core hydrogen |
| Red supergiants | Upper right, above red giants | Very massive stars in late stages |
| White dwarfs | Lower left (hot but faint) | Remnant cores of low/medium mass stars |
| Initial Mass | Main sequence lifetime | End state |
|---|---|---|
| < 0.5 M_sun | > 100 billion years | Red dwarf → white dwarf |
| 0.5-8 M_sun | ~1-15 billion years | Red giant → planetary nebula → white dwarf |
| 8-25 M_sun | ~10-50 million years | Red supergiant → supernova → neutron star |
| > 25 M_sun | ~1-10 million years | Red supergiant → supernova → black hole |
v = H_0 d
where v is the recessional velocity of a galaxy, d is its distance from us, and H_0 is the Hubble constant.
Key concepts:
| Method | Range | Principle |
|---|---|---|
| Trigonometric parallax | Up to ~100 pc | Measure the apparent shift of a star against background stars as the Earth orbits the Sun |
| Standard candles (Cepheid variables) | Up to ~30 Mpc | Period-luminosity relationship of Cepheid variable stars |
| Hubble's law | Beyond ~30 Mpc | v = H_0 d using measured red shifts |
Parallax:
d (parsec) = 1 / p (arcseconds) 1 parsec ≈ 3.09 x 10¹⁶ m ≈ 3.26 light-years
This is the definitive list of equations not on the AQA data sheet that you must know by heart. Organised by topic:
Analysis of recent AQA A-Level Physics papers reveals that certain topics appear more frequently than others. These are your highest-priority revision targets:
| Topic | Why it appears often |
|---|---|
| Photoelectric effect | Rich source of calculation and explanation questions |
| Circuit analysis (series/parallel, potential dividers) | Tests application of multiple rules simultaneously |
| SUVAT and projectile motion | Core calculation skills |
| Young modulus and stress-strain | Links to required practical 4 |
| Momentum and collisions | Tests conservation laws and calculation |
| SHM | Complex topic with many equation variants |
| Stationary waves | Links to required practical 1 |
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