Cambridge A-Level Physics

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AS foundations

Quantities and measurement

1.1, 1.2 - Quantities, units and estimatesLearn to communicate a measurement, recognise the SI base quantities used at AS Level, convert prefixes without losing powers of ten, and make estimates that catch impossible answers before they reach your calculator.
1.2 - Derived units and equation checksBuild derived units from SI base units and use them to test whether an equation could describe a physical situation. Learn what a unit check can expose, and why passing that check never proves an equation correct.
1.3 - Errors, precision and accuracyDistinguish systematic and random errors, correct a zero error, and judge accuracy separately from precision. Learn why a beautifully repeatable result can still be wrong, and choose an improvement that addresses the actual error.
1.3 - Combining uncertaintiesExpress measurement uncertainty in absolute, fractional and percentage forms. Combine uncertainties in calculated quantities, including differences, products, quotients and powers, and explain why a small difference can be much less certain than either original reading.

AS practical skills

Analysis and evaluation

Paper 3 - Trend lines, gradients and constantsLearn to choose a trend line, obtain a reliable gradient and intercept, and turn those graph features into physical constants. You will also use a tangent to describe how a changing quantity behaves at one instant.
Paper 3 - Testing relationships with uncertain dataLearn to estimate measurement uncertainty, compare two experimental estimates of a constant and state a conclusion that the evidence supports. You will distinguish agreement within uncertainty from proof that a physical model is true.
Paper 3 - Limitations and workable improvementsLearn to identify the measurement that most limits an investigation, explain its physical cause and propose a modification that would actually help. You will turn vague claims about “human error” into specific, testable improvements.

AS mechanics

Motion

2.1 - Displacement, velocity and motion graphsLearn to distinguish the route travelled from the change in position, calculate average speed and velocity, and read velocity from a displacement–time graph. These distinctions let you describe a journey without confusing “moving” with “getting further from the start”.
2.1 - Acceleration and velocity-time graphsLearn to describe acceleration with a direction, find acceleration from a velocity–time gradient, and find displacement from the area under the graph. You will also use tangents and numerical areas when the acceleration changes.
2.1 - Uniform acceleration and free fallDerive the equations for straight-line motion with constant acceleration, choose a signed equation for a journey or a falling object, and learn how an electronic fall timer can measure the acceleration of free fall. You will also use the quadratic formula when a flight time cannot be found by a s...
2.1 - Projectile motionLearn to treat a projectile as two perpendicular motions sharing one clock: constant horizontal velocity and constant vertical acceleration. Use that model for horizontal launches, angled launches, landing velocities and positions along a flight, while keeping its assumptions clear.

Forces and momentum

3.1 - Newton's laws, mass and weightLearn how forces change motion, why mass measures resistance to that change, and how Newton's three laws work together. Distinguish forces balancing on one object from interaction forces acting on different objects, then apply the distinction to mass, weight and supporting forces.
3.1 - Momentum and changing motionLearn to calculate momentum as a vector, connect resultant force with the rate at which momentum changes, and use a force–time area to find that change. Apply the ideas to stopping, rebounding and a force that varies throughout an impact.
3.2 - Drag and terminal velocityExplain how friction and drag change motion, why a falling object can stop accelerating while it is still moving, and how a parachute changes the balance of forces. Use force diagrams and the gradient of a velocity–time graph to connect the explanation to evidence.
3.3 - Collisions and momentum conservationUse total momentum to analyse collisions and separations, keep directions consistent, and distinguish an elastic collision from an inelastic one. Extend the same conservation law to two perpendicular directions when objects scatter in a plane.

Equilibrium and fluids

4.1, 4.2 - Moments, couples and centres of gravityRepresent an object's weight at its centre of gravity, calculate the turning effect of a force, and use the principle of moments. Distinguish a couple, which has a turning effect despite zero resultant force, from two forces that simply cancel.
4.2 - Forces in equilibriumRecognise both conditions for equilibrium, use a closed vector triangle for three coplanar forces, and combine force and moment equations to calculate support forces. Learn why balanced forces alone do not guarantee that an extended object will remain at rest.
4.3 - Density and pressure in fluidsCalculate density from mass and geometry, relate pressure to the normal force on an area, and derive the pressure difference between two depths in a fluid. Use the vertical depth and distinguish extra pressure due to a liquid from the total pressure.
4.3 - Upthrust and floatingExplain upthrust using the pressure difference between the top and bottom of an immersed object. Calculate the force from displaced fluid volume, distinguish upthrust from apparent weight, and use equilibrium to explain floating and submerged fractions.

Energy and materials

5.1, 5.2 - Work, kinetic energy and potential energyUse work to connect forces with energy changes, derive the expressions for gravitational potential energy and kinetic energy, and solve motion problems by keeping track of energy transfers.
5.1 - Power and efficiencyDistinguish how much energy is transferred from how quickly it is transferred, derive the force–speed relationship for power, and use efficiency to follow useful and unwanted energy transfers.
6.1, 6.2 - Springs and deformationDescribe how tensile and compressive forces deform solids, measure extension correctly, use Hooke's law, and distinguish the limit of proportionality from the elastic limit.
6.1 - Stress, strain and Young modulusSeparate a material's behaviour from a wire's dimensions using stress and strain, calculate Young modulus, and analyse a workable experiment to determine it from a metal wire.
6.2 - Energy stored in stretched materialsFind work done from force–extension graphs, derive the elastic-energy expressions for proportional deformation, and distinguish energy supplied during loading from energy recovered during unloading.

AS waves

Progressive waves

7.1 - Wave motion and the wave equationExplain how a progressive wave transfers energy, distinguish a particle's oscillation from the wave's motion, and read wave quantities from time and position graphs. Derive and use the relationship between wave speed, frequency and wavelength.
7.1 - Oscilloscope traces and wave measurementsUse an oscilloscope's time-base and y-gain to determine a signal's period, frequency and voltage amplitude. Separate changes to the display from changes to the signal, and use a sensor calibration when a voltage represents a physical oscillation.
7.1, 7.2 - Wave types and intensityCompare transverse and longitudinal waves, interpret displacement graphs without mistaking them for pictures of particle paths, and calculate intensity from power and area. Relate a wave's intensity to the square of its amplitude under the same propagation conditions.
7.3 - The Doppler effect for soundExplain why a moving sound source is heard at a different frequency by a stationary observer. Choose the sign in the moving-source Doppler equation from the wavefront spacing, calculate observed frequencies, and work backwards to a source speed.
7.4 - The electromagnetic spectrumRecognise electromagnetic waves as one transverse-wave family with a common speed in free space. Learn the approximate wavelength ranges of its principal regions, use frequency and wavelength to identify clear examples, and recall the visible range of 400–700 nm.
7.5 - Polarisation and Malus's lawExplain why polarisation identifies transverse waves, use Malus's law for initially plane-polarised light, and track intensity through successive polarising filters. Measure each angle from the polarisation direction entering that particular filter.

Superposition

8.1 - Stationary waves, nodes and antinodesLearn how overlapping waves add, how opposite-moving waves form a pattern with fixed nodes, and how experiments with strings, air and microwaves reveal that pattern. You will use node and antinode positions to measure wavelength and identify the modes that fit a system.
8.2 - Diffraction at gaps and edgesLearn why waves spread into a geometrical shadow and how the amount of spreading depends on wavelength compared with an opening. You will use ripple-tank observations to separate diffraction from changes of wave speed or frequency.
8.3 - Two-source interferenceLearn why two sources can make alternating regions of reinforcement and cancellation, what keeps their pattern stable, and how water, sound, light and microwave experiments demonstrate it. You will use double-slit fringes to determine a wavelength from measurable lengths.
8.4 - Measuring wavelengths with a diffraction gratingLearn how the spacing of a diffraction grating determines the directions of its bright orders. You will convert a line density into a slit separation, find allowed orders and use a screen measurement to determine light's wavelength.

AS electricity

Charge, energy and resistance

9.1 - Charge, current and drift velocityDescribe the charges that carry current, calculate how much charge passes a point, and use a microscopic model to connect current with carrier density, wire area and drift velocity.
9.2 - Potential difference and electrical powerInterpret potential difference as energy transferred per unit charge, derive the electrical-power relations, and calculate energy transfers while keeping power, charge and time distinct.
9.3 - Resistance and current-voltage characteristicsDefine resistance, state the condition in Ohm's law, and interpret the current–voltage characteristics of a constant-temperature metal, a filament lamp and a semiconductor diode.
9.3 - Resistivity and wire measurementsPredict how wire length and area affect resistance, distinguish resistance from resistivity, and determine resistivity from careful electrical and dimensional measurements.

Circuits

10.1 - Circuit diagrams and electromotive forceLearn to read and draw Cambridge's circuit symbols, place measuring instruments correctly, and describe a source's electromotive force in terms of energy per unit charge. Distinguish that energy supply from the energy transferred in a component without treating current as something the circuit co...
10.1 - Internal resistance and terminal voltageLearn why a real source's terminal p.d. can fall when it supplies more current. Use an ideal-source-plus-internal-resistance model, solve complete source–load circuits, and determine e.m.f. and internal resistance from measured voltage–current data.
10.2 - Kirchhoff's laws and circuit equationsLearn to use charge conservation at a junction and energy conservation around a closed loop. Translate connected circuits into signed equations, then solve simultaneous equations to find currents without assuming that current is used up or shared equally.
10.2 - Resistors in series and parallelDerive the series and parallel resistance rules from Kirchhoff's laws, then use them to simplify connected resistor networks. Track total current, branch current and p.d. as separate quantities so that a simplified circuit can be translated back into the original one.
9.3, 10.3 - Potential dividers and sensorsLearn how two series resistances divide a fixed supply p.d., why a connected load can change the output, and how thermistors and light-dependent resistors turn environmental changes into voltage changes. Always identify the two points between which the output is measured.
10.3 - Potentiometers and null methodsLearn how a uniform resistance wire provides a known p.d. per unit length, how a galvanometer detects a balance without drawing current from a test cell, and how balance lengths compare e.m.f.s or potential differences. Distinguish zero detector current from zero current in the working circuit.

AS particles

Atoms and fundamental particles

11.1 - The nuclear atom and nuclidesUse alpha-particle scattering evidence to explain the nuclear atom, identify protons, neutrons and electrons, and read nuclide notation without confusing the numbers. Convert microscopic masses using the unified atomic mass unit.
11.1 - Radiation, antiparticles and decay equationsDistinguish alpha, beta-minus, beta-plus and gamma radiation by their composition, mass and charge. Balance nuclear equations, include the correct neutrino in each beta decay, and explain why beta particles have a continuous range of energies.
11.2 - Quarks, hadrons and leptonsUse the six quark flavours and their charges to describe protons, neutrons, baryons and mesons. Distinguish hadrons from fundamental leptons, and explain beta decay as a change in quark flavour with the appropriate emitted lepton and antilepton.

A Level mechanics

Gravitation

13.1–13.3 - Gravitational forces and fieldsUse the gravitational field model to describe forces on test masses, apply Newton's inverse-square law, and derive field strength outside a spherical mass. Read field directions and graphs, and explain why a small region near a planet's surface can be treated as approximately uniform.
13.2 - Circular and geostationary orbitsUse gravity as the inward resultant for a circular orbit, relate orbital speed and period to centre distance, and identify every condition for a geostationary orbit. Explain orbital free fall without confusing weightlessness with an absence of gravity.
13.4 - Gravitational potential and energyDefine gravitational potential using a zero at infinity, interpret its negative sign, and calculate potential and potential-energy changes outside a spherical mass. Distinguish force per unit mass from energy per unit mass, and connect signed energy changes to work done by gravity or an external...

A Level thermal physics

Temperature and heating

14.1, 14.2 - Thermal equilibrium and temperature scalesLearn what temperature tells you about energy transfer, how a thermometer turns a changing physical property into a reading, and why the kelvin scale has a substance-independent meaning. You will convert between Celsius and kelvin without confusing a temperature with a temperature change.
14.3 - Specific heat capacityLearn why equal energy inputs can produce different temperature rises, how to calculate those changes and how to measure specific heat capacity electrically. You will check an energy balance and explain what heat losses and the apparatus do to an experimental result.
14.3 - Specific latent heatLearn why energy can change a substance's state without raising its temperature, distinguish fusion from vaporisation and calculate energy transfers through several stages. You will analyse melting and boiling measurements while separating the intended energy transfer from the surroundings' contr...

Gases and thermodynamics

15.1, 15.2 - Moles and the ideal gas equationLearn to connect the amount of gas with its particle count, pressure, volume and thermodynamic temperature. You will use both forms of the ideal gas equation, choosing consistent units and distinguishing absolute pressure from a gauge reading.
15.3 - Molecular motion and gas pressureUse the kinetic model of an ideal gas to explain pressure, derive it from molecular momentum changes, and connect a three-dimensional gas to measurable pressure and density.
15.3 - Molecular speeds and kinetic energyDistinguish mean speed, mean-square speed and root-mean-square speed, derive the link between temperature and average translational kinetic energy, and compare molecular speeds without mixing up particle mass and molar mass.
16.1 - Internal energy and changes of stateDescribe internal energy in terms of random molecular kinetic and potential energies, connect temperature changes with that energy, and explain why a phase change can increase internal energy without increasing temperature.
16.2 - The first law of thermodynamicsCalculate work during constant-pressure volume changes, use Cambridge's heating-and-work sign convention, and explain how compression or expansion can change a gas's internal energy and temperature.

A Level oscillations

A Level fields and circuits

Electric fields

18.1, 18.2 - Electric fields and parallel platesDescribe an electric field using the force on a positive test charge, interpret field lines, and calculate the field between parallel plates. Use that field to predict the force, acceleration and path of a charged particle, keeping its charge sign explicit.
18.3, 18.4 - Point charges and Coulomb's lawCalculate forces between point charges, recognise when a charged sphere can be represented by a point at its centre, and determine the strength and direction of a radial electric field. Add fields as vectors rather than treating their magnitudes as signed charges.
18.5 - Electric potential and potential energyDefine electric potential with a clear zero reference, combine potentials as scalars, and relate field direction to potential gradient. Use potential differences to calculate changes of potential energy and kinetic energy for positive and negative charges.

Capacitance

19.1 - Capacitance and capacitor combinationsDefine capacitance for two-plate capacitors and isolated spherical conductors, and distinguish stored charge from net charge. Derive and use the parallel and series combination rules from their physical charge and potential-difference conditions.
19.2 - Energy stored by a capacitorFind stored electric energy from a potential–charge graph and derive useful capacitor-energy expressions. Use them to compare charging conditions and calculate energy transferred during a discharge, keeping source energy distinct from the energy left stored.
19.3 - Capacitor discharge and the time constantExplain why capacitor charge, p.d. and discharge current decay exponentially through a resistor. Interpret their graph signs, use the time constant, and determine times or capacitance from voltage data while keeping stored energy distinct from remaining charge.

Magnetic forces

20.1, 20.4 - Magnetic field patterns and currentsMap magnetic fields around magnets and currents, and connect a solenoid's field to its winding direction. Use these patterns to explain why parallel current-carrying wires attract or repel, preparing for quantitative magnetic forces.
20.2 - Forces on current-carrying conductorsDetermine the direction and magnitude of the magnetic force on a current-carrying conductor. Define magnetic flux density through a measurable force, and use force balances and conductor angles without confusing current direction with electron motion.
20.3 - Charged particles and velocity selectionApply magnetic force to individual moving charges, explain circular particle paths, and select a beam speed using crossed electric and magnetic fields. Track the actual particle velocity and charge sign rather than substituting electron motion into a conventional-current rule.
20.3 - The Hall effect and magnetic measurementsExplain how sideways magnetic deflection of charge carriers establishes a Hall voltage. Derive its relation to current, carrier density and sample thickness, then use a calibrated Hall probe to measure magnetic flux density with a clear orientation and zero correction.

Induction and alternating currents

20.5 - Magnetic flux and flux linkageCalculate magnetic flux through an area and distinguish it from the flux linkage of a multi-turn coil. Use projected area and a clearly defined angle to track how rotating a coil changes signed linkage, even when magnetic flux density stays constant.
20.5 - Faraday's law and Lenz's lawConnect induction experiments to the rate of change of magnetic flux linkage. Calculate induced e.m.f. from changes and graph gradients, then use Lenz's law to determine its direction and explain the required energy transfer without confusing e.m.f. with current.
21.1 - Alternating current and root-mean-square valuesLearn to read a sinusoidal alternating current or voltage, calculate its heating effect in a resistor and connect its peak value to an equivalent steady value. You will distinguish an average current of zero from a non-zero mean transfer of energy.
21.2 - Half-wave and bridge rectificationLearn how diodes turn an alternating supply into a unidirectional output. Trace the complete current paths through a bridge rectifier and sketch half-wave and full-wave outputs on the same time scale as their input.
21.2 - Smoothing a rectified supplyLearn how a capacitor reduces the variation in rectified voltage. Explain the charging and discharging paths, compare the effects of capacitance and load resistance, and use a discharge trace to test the circuit model.

A Level quantum and nuclear physics

Quantum physics

22.1 - Photon energy and momentumDescribe photons as quanta of electromagnetic energy, calculate their energies in joules and electronvolts, and use their momentum to explain a mechanical transfer from light to a surface.
22.2 - The photoelectric effectExplain photoelectric emission using individual photons and work function, calculate threshold and maximum electron energies, and distinguish the effects of light intensity and frequency.
22.3 - Wave-particle duality and electron diffractionConnect wave and particle evidence for light and matter, explain an electron-diffraction pattern, and calculate de Broglie wavelengths from momentum and accelerating potential difference.
22.4 - Atomic energy levels and line spectraUse discrete electron energy levels to explain emission and absorption spectra, interpret transition diagrams, and calculate photon frequencies and wavelengths from energy differences.

Nuclear physics

23.1 - Mass defect and binding energyConnect rest mass with energy, balance nuclear reaction equations, and calculate a nucleus's mass defect and binding energy. Keep nuclear and atomic masses separate so that the energy calculation accounts for the same particles on both sides.
23.1 - Energy from fission and fusionUse the binding-energy-per-nucleon curve to explain why both splitting heavy nuclei and joining light nuclei can release energy. Balance complete reactions, compare total initial and final masses, and calculate the energy available to their products.
23.2 - Random decay, activity and half-lifeExplain why individual radioactive decays are unpredictable while large samples follow a predictable trend. Distinguish activity from detector count rate, correct for background, and use half-life and exponential decay to calculate the remaining nuclei or measured signal.

A Level applications

Medical imaging

24.1 - Ultrasound generation and imagingExplain how one piezoelectric transducer sends and detects ultrasound pulses. Use echo times to locate boundaries, compare acoustic impedances, and calculate reflection and attenuation while tracking the complete sound path.
24.2 - X-ray production and attenuationExplain electron-bombardment X-ray production and its spectrum. Calculate the shortest wavelength from the tube p.d., and use exponential attenuation and logarithmic data to describe transmission through matter.
24.2 - X-ray contrast and computed tomographyExplain how different transmitted X-ray intensities produce image contrast. Distinguish a projection from a reconstructed section, and describe how multiple angular views and successive sections build a three-dimensional CT image.
24.3 - Positrons and PET imagingExplain how a beta-plus tracer leads to detectable gamma-ray pairs. Use mass–energy and momentum conservation, calculate annihilation photon energy, and distinguish a coincidence line from the concentration image reconstructed from many events.

A Level practical skills

Analysis and uncertainty

Paper 5 - Linearising power laws and exponentialsLearn to choose derived quantities that turn physical relationships into straight lines. Use ordinary and logarithmic axes to determine constants, keeping units, logarithm bases and intercept meanings consistent.
Paper 5 - Error bars and worst acceptable linesLearn to carry uncertainty estimates into derived tables and graphs. Draw and distinguish a balanced best-fit line and an extreme acceptable line, then obtain gradient and intercept uncertainties without losing signs, units or the true origin.
Paper 5 - Constants, uncertainty and conclusionsLearn to turn fitted gradients and intercepts into physical constants with correct units. Propagate uncertainty through those equations, report results at justified precision and state exactly what agreement with a model or reference value establishes.