A Level Physics Notes (9702)

A Level Physics rewards precise definitions, clear reasoning and careful calculation. These notes follow the Cambridge International AS & A Level Physics syllabus (9702) topic by topic, from physical quantities and units to astronomy and cosmology. Each note gives the definitions in the exact form examiners credit, derives the key equations the syllabus asks you to derive, works through exam-style calculations with units and significant figures, and flags the misconceptions reported by Cambridge examiners. Equations in the data and formulae list are tagged, so you know which ones you must recall.

What every note gives you

• All 25 syllabus topics, AS (1 to 11) and A Level (12 to 25), in syllabus order.
• Definitions examiners credit, worded carefully, with "per unit" and "product" used correctly.
• The derivations the syllabus asks for: suvat, Δp = ρgΔh, pV = ⅓Nm⟨c²⟩, g = GM/r², the Hall voltage and more.
• Data and formulae tags, so you know which equations are printed in the paper and which you must recall.
• Practical skills built in: uncertainties, graphs and the Paper 3 and Paper 5 techniques that go with each topic.
• Exam-style questions with answers at the end of every note.

AS Level

1. 1Physical quantities and unitsSI base units and derived units, checking equations for homogeneity, prefixes, estimates, systematic and random errors, precision and accuracy, combining uncertainties, and scalars and vectors.~9 min read · AS
2. 2KinematicsDisplacement, velocity and acceleration, motion graphs, deriving the equations of uniformly accelerated motion, free fall and measuring g, and projectiles with uniform velocity in one direction and uniform acceleration in the other.~9 min read · AS
3. 3DynamicsMass and inertia, Newton's three laws, force as rate of change of momentum, weight, drag and terminal velocity, and conservation of momentum in elastic and inelastic collisions in one and two dimensions.~9 min read · AS
4. 4Forces, density and pressureCentre of gravity, moments, couples and torque, the principle of moments and the two conditions for equilibrium, vector triangles, density, pressure, deriving Δp = ρgΔh, and upthrust.~8 min read · AS
5. 5Work, energy and powerWork done by a force, conservation of energy, efficiency, power and deriving P = Fv, and deriving the formulas for gravitational potential energy and kinetic energy, with motion against resistive forces.~7 min read · AS
6. 6Deformation of solidsHooke's law and the spring constant, stress, strain and the Young modulus, the experiment to measure it, elastic and plastic deformation, and elastic potential energy from the area under a force–extension graph.~7 min read · AS
7. 7WavesProgressive waves and the words to describe them, reading an oscilloscope, deriving v = fλ, intensity and amplitude, transverse and longitudinal waves, the Doppler effect for a moving source, the electromagnetic spectrum and polarisation with Malus's law.~8 min read · AS
8. 8SuperpositionThe principle of superposition, how stationary waves form and how to find λ from nodes, experiments with strings, microwaves and air columns, diffraction, interference and coherence, the double slit λ = ax/D and the diffraction grating d sin θ = nλ.~9 min read · AS
9. 9ElectricityCurrent as a flow of charge carriers, quantised charge, Q = It and I = Anvq, potential difference and power, resistance and Ohm's law, I–V characteristics of a wire, diode and filament lamp, resistivity, and LDRs and thermistors.~7 min read · AS
10. 10D.C. circuitsE.m.f. and internal resistance, Kirchhoff's two laws and the conservation laws behind them, deriving series and parallel resistance, multi-loop circuits, potential dividers with sensors, and the potentiometer null method.~9 min read · AS
11. 11Particle physicsWhat α-particle scattering tells us about the nucleus, nuclide notation and isotopes, α, β⁻, β⁺ and γ radiation, antiparticles and neutrinos, decay equations, and quarks, hadrons and leptons with the quark changes in β decay.~7 min read · AS

A Level

1. 12Motion in a circleRadians and angular speed, why uniform circular motion needs a resultant force towards the centre, centripetal acceleration a = rω² = v²/r, and applying F = mv²/r to cars on bends, vertical circles and orbits.~5 min read · A Level
2. 13Gravitational fieldsGravitational field strength, Newton's law of gravitation, g = GM/r², gravitational potential and potential energy, circular orbits, Kepler's third law from first principles, and geostationary satellites.~5 min read · A Level
3. 14TemperatureThermal equilibrium and the direction of energy flow, the thermodynamic (kelvin) scale and absolute zero, specific heat capacity and specific latent heat, and the electrical and mixture methods for measuring them.~5 min read · A Level
4. 15Ideal gasesThe mole and the Avogadro constant, the ideal gas equation pV = nRT = NkT, the kinetic theory assumptions, deriving pV = ⅓Nm⟨c²⟩, and linking the mean kinetic energy of a molecule to temperature.~4 min read · A Level
5. 16ThermodynamicsInternal energy as the sum of random kinetic and potential energies of molecules, work done on or by a gas W = pΔV, and the first law of thermodynamics ΔU = q + W with its sign convention.~4 min read · A Level
6. 17OscillationsDescribing oscillations, simple harmonic motion defined by a = −ω²x, displacement, velocity and acceleration equations and graphs, energy in SHM, and damping, forced oscillations and resonance.~5 min read · A Level
7. 18Electric fieldsElectric field strength, uniform fields between parallel plates, the motion of charged particles in a uniform field, Coulomb's law for point charges, and electric potential and its link to field strength.~4 min read · A Level
8. 19CapacitanceCapacitance C = Q/V, capacitors in series and parallel, the energy stored as ½QV, the capacitance of an isolated sphere, and the exponential discharge of a capacitor through a resistor with time constant RC.~4 min read · A Level
9. 20Magnetic fieldsMagnetic field patterns, the force on a current-carrying conductor F = BIL sin θ, forces on moving charges F = BQv, circular paths, velocity selection and the Hall effect, forces between wires, and electromagnetic induction with Faraday’s and Lenz’s laws.~6 min read · A Level
10. 21Alternating currentsDescribing sinusoidal alternating currents, peak and root-mean-square values, mean power in a resistor, and rectification with one diode, a bridge of four diodes, and smoothing with a capacitor.~3 min read · A Level
11. 22Quantum physicsPhotons with E = hf and momentum p = E/c, the electronvolt, the photoelectric effect and Einstein’s equation, wave–particle duality and the de Broglie wavelength, and energy levels with emission and absorption line spectra.~5 min read · A Level
12. 23Nuclear physicsMass–energy equivalence, mass defect and binding energy, the binding energy per nucleon curve and why fission and fusion release energy, and the random, spontaneous nature of radioactive decay with activity, decay constant and half-life.~5 min read · A Level
13. 24Medical physicsUltrasound production by piezoelectric crystals, acoustic impedance and reflection at boundaries, A-scans; X-ray production, attenuation and CT scanning; and PET scanning with tracers and electron–positron annihilation.~5 min read · A Level
14. 25Astronomy and cosmologyLuminosity and radiant flux intensity, standard candles, Wien's displacement law and the Stefan–Boltzmann law to find stellar temperatures and radii, redshift, Hubble's law and the evidence for an expanding universe.~4 min read · A Level

Exam special notes

Built from the Cambridge examiner reports and mark schemes: where students actually lose marks, and how to stop it.

1. ★A Level Physics 9702: Definitions You Must KnowEvery definition 9702 asks for, AS and A Level, in one place: worded precisely enough to earn the mark, with the key words examiners look for and the near-misses that score zero.~8 min read · Definitions
2. ★A Level Physics 9702: Paper 3 Practical and Paper 5 Planning GuideHow to score on the practical papers: tables and significant figures, graphs and gradients, uncertainties, the limitations-and-improvements question on Paper 3, and planning, log graphs, error bars and worst-fit lines on Paper 5.~7 min read · Practical guide

Full syllabus map

Practise with full mark schemes in the free Paper Generator.

Frequently asked questions