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A-level Physics revision checklist

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Which option unit do you sit?

Five of the units below are AQA option units and you sit one of them. Tick yours to leave the rest out of this list, out of whole-course practice and out of the day plan. Change the setting to restore them.

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Measurements

SI base and derived units AQA 7408 3.1.1 · CIE 9702 1.1.1, 1.2.1, 1.2.2, 1.2.3, 15.1.1 · OCR A H556 2.1.1(a), 2.1.2(a), 2.1.2(b), 2.1.2(c), 2.1.2(d), 3.2.1(b) · Edexcel 9PH0 1

Name the six SI base quantities used at A-level, and unpack any derived unit back into them.
Check an equation for homogeneity by reducing every term to base units, and say what a failed check proves and what a passed one does not.

Prefixes, labels and unit conversions AQA 7408 3.1.1 · CIE 9702 1.2.4 · OCR A H556 2.1.2(e), 2.1.2(f), 4.2.5(c) · Edexcel 9PH0 94

Use your board's SI prefixes with standard form, and convert between units of the same quantity, such as J and eV, or J and kW h.
Head a table column and label a graph axis in the quantity / unit form, so the entries are pure numbers.

Uncertainty and error AQA 7408 3.1.2 · CIE 9702 1.3.1, 1.3.2, 1.3.3 · OCR A H556 1.1.3(c), 1.1.4(d), 1.1.4(e), 2.2.1(a), 2.2.1(b), 2.2.1(c), 2.2.1(d) · Edexcel 9PH0 4

Tell a random error from a systematic one, and pick the treatment that actually reduces each.
Use precision, accuracy, resolution, repeatability and reproducibility with the meanings mark schemes use.
Estimate an uncertainty from an instrument's resolution, or from the range of a set of repeats.
Move between absolute, fractional and percentage uncertainty, and combine them through sums, products and powers.
Put error bars on a graph and get the uncertainty in the gradient from the steepest and shallowest lines.

Estimation and orders of magnitude AQA 7408 3.1.3 · CIE 9702 1.1.2 · OCR A H556 2.1.1(b) · Edexcel 9PH0 3

Give a quantity's order of magnitude as the nearest power of ten.
Carry a handful of benchmarks, chain them through an equation, and use the result to check a calculated value.

Mechanics

Scalars and vectors AQA 7408 3.4.1.1 · CIE 9702 1.4.1, 1.4.2, 1.4.3, 4.2.3 · OCR A H556 2.3.1(a), 2.3.1(b), 2.3.1(c), 2.3.1(d), 3.2.3(f) · Edexcel 9PH0 12, 13, 14

Classify quantities as scalars or vectors, using the standard paired examples.
Add two perpendicular vectors by calculation, and any other pair by scale drawing.
Subtract one coplanar vector from another by reversing it and adding, and use that to find a change in a vector quantity.
Resolve a vector into two perpendicular components, including weight on an inclined plane.
State and use the equilibrium condition for two or three coplanar forces acting at a point.

Moments and equilibrium AQA 7408 3.4.1.2 · CIE 9702 4.1.1, 4.1.2, 4.1.3, 4.1.4, 4.2.1, 4.2.2 · OCR A H556 3.2.3(a), 3.2.3(b), 3.2.3(c), 3.2.3(d), 3.2.3(e) · Edexcel 9PH0 23, 24

Calculate the moment of a force as force times perpendicular distance from the point to the line of action.
Recognise a couple, and give its torque as one force times the separation of the lines of action.
Apply the principle of moments, choosing the pivot that deletes an unknown force.
Place an object's weight at its centre of mass, which for a uniform regular solid is its geometric centre.
Separate centre of mass from centre of gravity, and for OCR, find the centre of gravity of an irregular lamina with a plumb line.

Motion graphs and the SUVAT equations AQA 7408 3.4.1.3 · CIE 9702 2.1.1, 2.1.2, 2.1.3, 2.1.4, 2.1.5, 2.1.6, 2.1.7 · OCR A H556 3.1.1(a), 3.1.1(b), 3.1.1(c), 3.1.1(d), 3.1.2(a)(i), 3.1.2(b)(i), 3.1.2(c) · Edexcel 9PH0 9, 10, 11

Use v = Δs/Δt and a = Δv/Δt, and tell an average value from an instantaneous one.
Read gradients and areas off displacement-time, velocity-time and acceleration-time graphs, curved ones included.
Choose the constant-acceleration equation that omits the quantity you neither have nor want.
Derive all four constant-acceleration equations from the definitions of velocity and acceleration.
Spot when the acceleration is not constant, and abandon SUVAT for the area under a graph.

Projectile motion AQA 7408 3.4.1.4 · CIE 9702 2.1.9 · OCR A H556 3.1.3(a), 3.1.3(b) · Edexcel 9PH0 9, 15

Explain the independence of horizontal and vertical motion in a uniform gravitational field.
Solve projectile problems by treating the two directions separately, linked only by time.
Describe qualitatively how air resistance changes a projectile's trajectory.

Newton's laws and the resultant force AQA 7408 3.4.1.5 · CIE 9702 3.1.2, 3.1.5 · OCR A H556 3.2.1(a), 3.2.1(d), 3.2.1(e), 3.2.1(f), 3.5.1(a) · Edexcel 9PH0 16, 17, 20

State and apply all three laws of motion in appropriate situations.
Use ΣF = ma for constant mass, starting from a labelled free-body diagram.
Identify genuine third-law pairs, and explain why weight and the normal contact force are not one.

Mass and weight AQA 7408 3.4.1.1 · CIE 9702 3.1.1, 3.1.6 · OCR A H556 3.2.1(c) · Edexcel 9PH0 18

Separate mass, a scalar in kilograms, from weight, a force in newtons.
Use W = mg with g as the gravitational field strength at the object's location, and state what a beam balance and a newton meter each measure.

Drag and terminal speed AQA 7408 3.4.1.4 · CIE 9702 3.2.1, 3.2.2, 3.2.3 · OCR A H556 3.2.2(a), 3.2.2(b), 3.2.2(c), 3.2.2(d)(i) · Edexcel 9PH0 17

Describe friction, lift and drag qualitatively, including that air resistance increases with speed.
Explain terminal speed using Newton's laws, and sketch the velocity-time graph it produces.
Apply the same balance argument to a parachutist's two terminal speeds and to a vehicle's maximum speed.

Momentum and impulse AQA 7408 3.4.1.6 · CIE 9702 3.1.3, 3.1.4, 3.3.1, 3.3.2, 3.3.3, 3.3.4 · OCR A H556 3.5.1(b), 3.5.1(c), 3.5.1(d), 3.5.1(e), 3.5.2(a), 3.5.2(b), 3.5.2(c) · Edexcel 9PH0 21, 22, 97, 99, 101, 102

Calculate momentum as p = mv, and handle it as a signed number in one dimension.
Apply conservation of linear momentum to collisions and to explosions, and to a two-dimensional collision by resolving into components.
Derive E_k = p²/(2m) and use it to move between a momentum and a kinetic energy.
Use F = Δ(mv)/Δt and impulse FΔt = Δ(mv), including the area under a force-time graph.
Tell elastic from inelastic by comparing total kinetic energy before and after, and by comparing the relative speeds of approach and separation.
Explain crumple zones, airbags and bent knees through contact time.

Work, energy and power AQA 7408 3.4.1.7 · CIE 9702 5.1.1, 5.1.3, 5.1.4, 5.1.5, 5.1.6, 5.1.7 · OCR A H556 3.3.1(a), 3.3.1(b), 3.3.1(e), 3.3.3(a), 3.3.3(b), 3.3.3(c) · Edexcel 9PH0 25, 29, 30

Calculate work as W = Fs cos θ, and spot the forces that do no work at all or negative work.
Take the work from the area under a force-displacement graph when the force varies.
Use P = ΔW/Δt, derive P = Fv from W = Fs, and use it, top-speed problems included.
Find efficiency as useful output over input, working in powers or in energies.

Conservation of energy AQA 7408 3.4.1.8 · CIE 9702 5.1.2, 5.2.1, 5.2.2, 5.2.3, 5.2.4 · OCR A H556 3.3.1(c), 3.3.1(d), 3.3.2(a), 3.3.2(b), 3.3.2(c) · Edexcel 9PH0 26, 27, 28

State the principle of conservation of energy and use it as an energy balance.
Calculate kinetic energy and changes in gravitational potential energy.
Derive ΔE_p = mgΔh from W = Fs, and E_k = ½mv² from the equations of motion.
Balance energy transfers that include work done against friction or drag.

Materials

Density and Hooke's law AQA 7408 3.4.2.1 · CIE 9702 4.3.1, 6.1.1, 6.1.2, 6.1.3, 6.1.4, 6.2.1, 6.2.2, 6.2.3, 6.2.4 · OCR A H556 3.2.4(a), 3.4.1(a), 3.4.1(b), 3.4.1(c), 3.4.1(d)(i), 3.4.2(a), 3.4.2(b), 3.4.2(f) · Edexcel 9PH0 49, 53, 55, 58

Use $\rho = m/V$ , and get the g cm⁻³ to kg m⁻³ conversion the right way round.
Apply $F = k\Delta L$ while it holds, and say what the spring constant belongs to.
Separate the limit of proportionality from the elastic limit.
Find the stored energy from the area under a force-extension graph, and account for the energy that never comes back after plastic deformation.

Stress, strain and the Young modulus AQA 7408 3.4.2.2 · CIE 9702 6.1.5, 6.1.6 · OCR A H556 3.4.2(c), 3.4.2(d)(i), 3.4.2(d)(ii), 3.4.2(e) · Edexcel 9PH0 54, 56, 57

Define tensile stress and tensile strain, and give the unit of each.
Use the Young modulus as stress over strain, and assemble the $FL/A\Delta L$ form yourself when you need it.
Take E from the gradient of the straight part of a stress-strain graph.
Read yield, breaking stress and brittle failure off a stress-strain curve, and describe one method of measuring E for a wire.
Tell the ductile, brittle and polymeric stress-strain shapes apart, and explain why rubber stiffens as it stretches and loses energy round its hysteresis loop.

Fluids: pressure, upthrust and viscosity CIE 9702 4.3.2, 4.3.3, 4.3.4, 4.3.5, 4.3.6 · OCR A H556 3.2.4(b), 3.2.4(c) · Edexcel 9PH0 50, 51

Use p = F/A for a solid, a liquid or a gas, and say what changes between the three.
Derive Δp = ρgΔh from the definitions of pressure and density, and use p = ρgh for the pressure due to a column of fluid.
Explain upthrust as the weight of fluid displaced, and state the condition for floating.
Use Stokes' law for the viscous drag on a small sphere, and find its terminal velocity.

Waves

Progressive waves AQA 7408 3.3.1.1 · CIE 9702 7.1.1, 7.1.2, 7.1.3, 7.1.4, 7.1.5, 7.1.6, 7.1.7 · OCR A H556 4.4.1(a), 4.4.1(b)(i), 4.4.1(b)(ii), 4.4.1(c), 4.4.1(d), 4.4.1(g) · Edexcel 9PH0 59, 60, 66, 70

Say what a progressive wave transfers, and what the particles of the medium do instead.
Define amplitude, wavelength, frequency, period and phase difference.
Tell a displacement-distance graph from a displacement-time graph, and take the right reading off each.
Move between speed, frequency, wavelength and period using $c = f\lambda$ and $f = 1/T$ .
Read a period, a frequency and an amplitude off an oscilloscope from its time-base and y-gain settings.

Longitudinal and transverse waves AQA 7408 3.3.1.2 · CIE 9702 7.2.1, 7.2.2 · OCR A H556 4.4.1(a), 4.4.1(e) · Edexcel 9PH0 61, 62, 63

Classify a wave as transverse or longitudinal from the direction of its oscillations.
Mark the compressions and rarefactions on the displacement-distance graph of a longitudinal wave, and say why they are not at the crests.

Polarisation and electromagnetic waves AQA 7408 3.3.1.2 · CIE 9702 7.4.1, 7.4.2, 7.4.3, 7.5.1, 7.5.2 · OCR A H556 4.4.1(f)(i), 4.4.2(a), 4.4.2(b), 4.4.2(c) · Edexcel 9PH0 82

Describe what a polarising filter does to unpolarised light, and what a second, crossed filter does next.
Explain why polarisation is evidence that light is transverse, and why sound, longitudinal in air, cannot be polarised.
CIE only: use Malus's law on plane-polarised light passing one filter, and then a series of them.
Order the regions of the electromagnetic spectrum by wavelength, all of them travelling at c in a vacuum, with the visible range in nanometres.

Stationary waves on strings AQA 7408 3.3.1.3 · CIE 9702 8.1.1, 8.1.2, 8.1.3, 8.1.4 · OCR A H556 4.4.3(a)(i), 4.4.3(b), 4.4.4(a), 4.4.4(b), 4.4.4(c), 4.4.4(d), 4.4.4(e)(i), 4.4.4(f), 4.4.4(g) · Edexcel 9PH0 63, 67, 68

Describe how two travelling waves superpose to form a stationary wave, and define node and antinode.
Use the node and antinode spacings, $\lambda/2$ and $\lambda/4$ , to get from a measured distance to a wavelength.
Find the allowed wavelengths of a string fixed at both ends, and use $v = \sqrt{T/\mu}$ and the first-harmonic frequency equation.
State the amplitude and phase relationships that separate stationary waves from progressive ones.

Stationary waves in air columns AQA 7408 3.3.1.3 · CIE 9702 8.1.2, 8.1.4 · OCR A H556 4.4.4(a), 4.4.4(e)(i), 4.4.4(e)(ii), 4.4.4(g)

Say why a closed end of a pipe must be a displacement node and an open end an antinode.
Work out the harmonics of an air column in a closed and in an open tube, and say why a closed tube sounds only the odd ones.
Describe the resonance-tube method for the speed of sound, and say why it uses two lengths rather than one.

Refraction and Snell's law AQA 7408 3.3.2.3 · OCR A H556 4.4.1(f)(i), 4.4.2(d)(i) · Edexcel 9PH0 71, 72

Use refractive index as a ratio of speeds, and say what happens to frequency and to wavelength at a boundary.
Apply Snell's law, predicting which way the ray bends before calculating how far.
Measure the refractive index of a solid by tracing a ray through a block and taking the gradient of sin θ₁ against sin θ₂.

Total internal reflection and optical fibres AQA 7408 3.3.2.3 · OCR A H556 4.4.2(d)(i), 4.4.2(e) · Edexcel 9PH0 73, 74

State both conditions for total internal reflection, and calculate a critical angle.
Describe a step-index optical fibre and the three jobs the cladding does.
Separate modal from material dispersion, and match each one to its fix.

Diffraction and the single slit AQA 7408 3.3.2.2 · CIE 9702 8.2.1, 8.2.2 · OCR A H556 4.4.1(f)(i) · Edexcel 9PH0 83

Describe diffraction at a gap, and state when the spreading is greatest.
Use Huygens' construction, secondary wavelets and their envelope, to explain what a wave does at a slit and at an obstacle.
Sketch the single-slit intensity pattern for monochromatic and for white light, and say how slit width and wavelength change it.

Interference and Young's double slit AQA 7408 3.3.2.1 · CIE 9702 8.3.1, 8.3.2, 8.3.3, 8.3.4 · OCR A H556 4.4.3(a)(i), 4.4.3(c), 4.4.3(d), 4.4.3(e), 4.4.3(f), 4.4.3(g)(i) · Edexcel 9PH0 65

Predict constructive or destructive interference from a path difference.
Explain what coherence means, and why a pattern you can see needs it.
Use $w = \lambda D / s$ , keeping straight which of the three lengths is the large one.
Describe the white-light pattern, and give a specific laser safety precaution.

Diffraction gratings AQA 7408 3.3.2.2 · CIE 9702 8.4.1, 8.4.2 · OCR A H556 5.5.2(g), 5.5.2(h) · Edexcel 9PH0 84

Explain why many slits give sharper and brighter maxima than two.
Use $d \sin\theta = n\lambda$ , getting d from the number of lines per millimetre.
Work out the highest order that can exist, and give uses of gratings.

Lenses and images Edexcel 9PH0 75, 76, 77, 78, 79, 80, 81

Move between focal length and power in dioptres with P = 1/f, carrying the sign for a diverging lens.
Draw ray diagrams for a thin converging lens, locating real and virtual images.
Use the thin lens equation and m = v/u to find image positions and sizes.
Read a negative v as a virtual image, and say what a viewer would see.

Quantum phenomena

The photoelectric effect and the photon AQA 7408 3.2.2.1 · CIE 9702 22.1.1, 22.1.2, 22.1.3, 22.1.4, 22.1.5, 22.2.1, 22.2.2, 22.2.3, 22.2.4, 22.2.5 · OCR A H556 4.5.1(a), 4.5.1(b), 4.5.1(c), 4.5.1(d), 4.5.2(a)(i), 4.5.2(b), 4.5.2(c), 4.5.2(d), 4.5.2(e), 4.5.2(f) · Edexcel 9PH0 91, 92, 93, 94, 95

Describe the photoelectric observations that a wave model of light cannot explain.
Explain threshold frequency using photons, and define work function and stopping potential.
Apply the photoelectric equation hf = φ + E_k(max), converting a work function from eV first.

The photoelectric graph and measuring h AQA 7408 3.2.2.1 · CIE 9702 22.2.4 · OCR A H556 4.5.1(e)(i), 4.5.2(c) · Edexcel 9PH0 93

Read the E_k(max) against frequency graph, naming its gradient and both intercepts.
Estimate the Planck constant from the pd at which an LED first lights, using eV = hc/λ.

Collisions of electrons with atoms AQA 7408 3.2.2.2 · CIE 9702 22.1.4, 22.4.1, 22.4.3 · OCR A H556 4.5.1(d), 5.5.2(a), 5.5.2(d) · Edexcel 9PH0 94

Distinguish excitation from ionisation in collisions between electrons and atoms.
Explain how excitation and ionisation operate inside a fluorescent tube.
Use the electronvolt, converting between eV and joules in both directions.

Energy levels and photon emission AQA 7408 3.2.2.3 · CIE 9702 22.4.1, 22.4.2, 22.4.3 · OCR A H556 5.5.2(a), 5.5.2(b), 5.5.2(c), 5.5.2(d), 5.5.2(e), 5.5.2(f) · Edexcel 9PH0 96

Interpret line spectra as evidence for transitions between discrete energy levels.
Use hf = E₁ − E₂ for photon emission, with levels quoted in J or eV.
Explain why each element's line spectrum is unique.

Wave-particle duality AQA 7408 3.2.2.4 · CIE 9702 22.3.1, 22.3.2, 22.3.3, 22.3.4 · OCR A H556 4.5.3(a), 4.5.3(b), 4.5.3(c) · Edexcel 9PH0 7, 86, 87, 90

State the two-way evidence, electron diffraction for the wave nature of particles and the photoelectric effect for the particle nature of light.
Use the de Broglie wavelength λ = h/mv, finding v from a kinetic energy where needed.
Explain how and why the diffraction changes when a particle's momentum changes.
Say why wave behaviour never shows up in everyday objects.

Particles

Constituents of the atom AQA 7408 3.2.1.1 · CIE 9702 11.1.2, 11.1.3, 11.1.4, 11.1.5 · OCR A H556 6.4.1(b), 6.4.1(d) · Edexcel 9PH0 130

Quote the charge and mass of the proton, neutron and electron in SI and relative units.
Calculate the specific charge of particles, nuclei and ions.
Use nuclide notation with Z and A, and explain what isotopes are and why isotopic data is useful.

Stable and unstable nuclei AQA 7408 3.2.1.2 · CIE 9702 11.1.6, 11.1.10, 11.1.11 · OCR A H556 6.4.1(e), 6.4.3(c) · Edexcel 9PH0 170

Explain the role of the strong nuclear force, including its attractive and repulsive ranges.
Write balanced equations for alpha and beta-minus decay.
Explain why the neutrino was hypothesised from the beta-decay energy spectrum.

Antimatter and photons AQA 7408 3.2.1.3 · CIE 9702 11.1.8 · OCR A H556 6.4.2(a), 6.4.2(b), 6.4.4(c) · Edexcel 9PH0 137, 138, 141

Compare particles and antiparticles by mass, charge and rest energy in MeV.
Use the photon model E = hf = hc/λ, moving between joules and electronvolts.
Describe annihilation, and calculate the minimum energy or frequency of each photon.
Describe pair production, including the threshold energy and the job the nearby nucleus does.
Work in MeV and GeV, and on Edexcel in MeV/c² and GeV/c², converting to and from SI units.

Particle interactions and exchange particles AQA 7408 3.2.1.4 · OCR A H556 6.4.2(h), 6.4.2(k) · Edexcel 9PH0 143

Name the four fundamental interactions, explain what an exchange particle does, and say why gravity sits outside the tested picture.
Identify the virtual photon and the W bosons as the exchange particles of the electromagnetic and weak interactions.
Draw and interpret simple diagrams for β⁻ and β⁺ decay, electron capture and electron-proton collisions.
Choose the right W boson for a given process, and say why the weak interaction is the one at work.

Classification of particles AQA 7408 3.2.1.5 · CIE 9702 11.2.6 · OCR A H556 6.4.2(c), 6.4.2(d) · Edexcel 9PH0 140

Classify particles as hadrons (baryons or mesons) or leptons, with the specified examples.
Say which interactions each family feels, and why that is the sorting rule.
Use baryon number and the two lepton numbers as conserved quantum numbers.
Describe strange particles, produced in pairs by the strong interaction and decaying by the weak.

Quarks and the hadrons built from them AQA 7408 3.2.1.6 · CIE 9702 11.2.1, 11.2.2, 11.2.3 · OCR A H556 6.4.2(e), 6.4.2(f), 6.4.2(g) · Edexcel 9PH0 141

Use the booklet's table of charge, baryon number and strangeness for the u, d and s quarks and their antiquarks.
Build the proton, neutron, antiproton, antineutron, pions and kaons from quarks.
Check any composition by adding thirds, for charge, baryon number and strangeness alike.

Decays at quark level AQA 7408 3.2.1.6 · CIE 9702 11.2.4 · OCR A H556 6.4.2(i), 6.4.2(k), 6.4.2(l)

Describe the decay of the neutron in terms of its quarks.
Take any decay apart at quark level, naming the quark that changed flavour and the W boson that carried the charge away.

The conserved quantities AQA 7408 3.2.1.7 · CIE 9702 11.1.9, 11.2.5 · OCR A H556 6.4.2(h), 6.4.2(i), 6.4.2(j) · Edexcel 9PH0 142, 143

Describe the quark character change in β⁻ and β⁺ decay.
Check interactions against conservation of charge, baryon number, lepton number and strangeness.

Energy, momentum and particle tracks AQA 7408 3.2.1.7 · Edexcel 9PH0 135

Recognise that energy and momentum are conserved in every interaction, and that either can forbid one.
For Edexcel, interpret a particle-track photograph, reading the sign of a charge from the curl, the momentum from the radius and lost energy from a spiral.

Electricity

Current, charge and potential difference AQA 7408 3.5.1.1 · CIE 9702 9.1.2, 9.1.3, 9.2.1, 9.2.2 · OCR A H556 4.1.1(a), 4.1.1(b), 4.1.1(c), 4.1.1(d), 4.2.2(a), 4.2.2(d), 4.2.2(e) · Edexcel 9PH0 31, 32

Use I = ΔQ/Δt, and give the coulomb as one ampere second.
Use V = W/Q, where one volt is one joule per coulomb.
Calculate the speed of a charge accelerated from rest through a pd in a vacuum, using eV = ½mv².

Charge carriers, drift speed and resistance AQA 7408 3.5.1.1 · CIE 9702 9.1.1, 9.1.4, 9.3.1, 9.3.2 · OCR A H556 4.1.1(e), 4.1.1(f), 4.1.2(a), 4.1.2(b), 4.1.2(c), 4.2.3(a) · Edexcel 9PH0 41

Name the carriers in each case: delocalised electrons in a metal, ions of both signs in an electrolyte.
State R = V/I as a definition, and distinguish conventional current from electron drift.
Relate current to carrier number density and drift speed with I = nAvq.

Current-voltage characteristics AQA 7408 3.5.1.2 · CIE 9702 9.3.2, 9.3.3, 9.3.4, 9.3.5 · OCR A H556 4.2.3(a), 4.2.3(b), 4.2.3(c)(i) · Edexcel 9PH0 33, 38

Sketch and interpret the I-V characteristics of an ohmic conductor, a filament lamp and a semiconductor diode, and explain the shape of each.
Quote Ohm's law as the special case I ∝ V under constant physical conditions, and read resistance off any characteristic as V/I at a point.
Treat the meters as ideal, with zero resistance in the ammeter and infinite resistance in the voltmeter.

Resistivity and temperature AQA 7408 3.5.1.3 · CIE 9702 9.3.6, 9.3.8 · OCR A H556 4.2.4(a)(i), 4.2.4(a)(ii), 4.2.4(b), 4.2.4(c) · Edexcel 9PH0 39, 40, 47

Move between a wire's resistance and its material's resistivity with ρ = RA/L, in Ω m.
Say what warming does to a metal's resistance, and why an ntc thermistor does the opposite.
Give thermistor applications, reading a resistance-temperature graph as the calibration.

Light-dependent resistors and superconductivity AQA 7408 3.5.1.3 · OCR A H556 4.2.4(b) · Edexcel 9PH0 48

Model an LDR's fall in resistance as light freeing extra conduction electrons, and contrast it with the metal.
Describe superconductivity below a critical temperature, with its two examinable applications.

Circuit symbols and Kirchhoff's laws AQA 7408 3.5.1.4 · CIE 9702 10.1.1, 10.1.2, 10.2.1, 10.2.2 · OCR A H556 4.1.1(g), 4.2.1(a), 4.2.1(b), 4.3.1(a), 4.3.1(b) · Edexcel 9PH0 34, 35

Recall the standard circuit symbols, and draw and interpret a circuit diagram built from them.
Apply conservation of charge at junctions and conservation of energy round loops.

Series, parallel and power AQA 7408 3.5.1.4 · CIE 9702 9.2.3, 10.2.3, 10.2.4, 10.2.5, 10.2.6, 10.2.7 · OCR A H556 4.2.5(a), 4.2.5(b), 4.3.1(c), 4.3.1(d), 4.3.1(e), 4.3.1(f) · Edexcel 9PH0 36, 37

Handle the series and parallel rules for current, pd and resistance, cells in series and identical cells in parallel included.
Analyse a circuit carrying more than one source of e.m.f., adding the emfs that drive the same way round and subtracting the one that opposes.
Pick the right energy or power equation, E = IVt and the three forms of P, from what the circuit shares.

The potential divider and its output AQA 7408 3.5.1.5 · CIE 9702 10.3.1 · OCR A H556 4.3.3(a), 4.3.3(c)(i) · Edexcel 9PH0 42, 43

Explain why series resistors share the supply pd in the ratio of their resistances.
Calculate a divider's output, and supply a variable pd with a sliding contact.
Describe how the potential varies along a uniform current-carrying wire, and take a pd off a length of it.
Predict what connecting a load across the output does to that output, and how to keep the effect small.

Sensing circuits and the potentiometer AQA 7408 3.5.1.5 · CIE 9702 9.3.7, 10.3.2, 10.3.3, 10.3.4 · OCR A H556 4.2.3(d), 4.3.3(b) · Edexcel 9PH0 44

Design sensing dividers from thermistors and LDRs, choosing which resistor carries the output.
For CIE, compare potential differences on a potentiometer, and say what the galvanometer does in a null method.

EMF and internal resistance AQA 7408 3.5.1.6 · CIE 9702 10.1.3, 10.1.4, 10.1.5 · OCR A H556 4.2.2(b), 4.2.2(c), 4.2.2(d), 4.3.2(a), 4.3.2(b), 4.3.2(c)(i), 4.3.2(c)(ii) · Edexcel 9PH0 45, 46

Define emf as the energy given to each unit of charge, ε = E/Q, and keep it distinct from terminal pd.
Work circuits where r cannot be neglected, using ε = I(R + r) and V = ε − Ir.
Determine ε and r from a graph of terminal pd against current.

Periodic motion

Circular motion AQA 7408 3.6.1.1 · CIE 9702 12.1.1, 12.1.2, 12.1.3, 12.2.1, 12.2.2, 12.2.3, 12.2.4 · OCR A H556 5.2.1(a), 5.2.1(b), 5.2.1(c), 5.2.2(a), 5.2.2(b), 5.2.2(c), 5.2.2(d)(i) · Edexcel 9PH0 103, 104, 105, 106, 107

Explain why constant-speed circular motion is accelerated motion, and why it needs a centripetal force.
Work in radians, with ω = v/r = 2πf.
Derive a = v²/r from a vector triangle, and see where its inward direction comes from.
Apply a = v²/r = ω²r and F = mv²/r = mω²r, and name the real force supplying it each time.

Simple harmonic motion AQA 7408 3.6.1.2 · CIE 9702 17.1.1, 17.1.2, 17.1.3, 17.1.4, 17.1.5 · OCR A H556 5.3.1(a), 5.3.1(b), 5.3.1(c)(i), 5.3.1(d), 5.3.1(e), 5.3.1(f), 5.3.1(g) · Edexcel 9PH0 182, 184, 185

Move between frequency, period and angular frequency, with f = 1/T and ω = 2πf.
State and apply the SHM condition, a ∝ −x, and the defining equation a = −ω²x.
Use x = A cos ωt and v = ±ω√(A² − x²) to place an oscillator at any moment.
Locate v_max = ωA and a_max = ω²A, and say where in the cycle each one happens.
Sketch the x, v and a against t graphs and connect them through their gradients.

The mass on a spring and the simple pendulum AQA 7408 3.6.1.3 · CIE 9702 17.2.1 · OCR A H556 5.3.1(c)(ii), 5.3.2(a) · Edexcel 9PH0 2, 181, 183

Use T = 2π√(m/k) for a mass-spring system, and say why g never appears in it.
Use T = 2π√(l/g) for a simple pendulum, with the small-angle condition stated.
Get k or g from the gradient of a T² graph, the way required practical 7 does.

Energy in an oscillation and damping AQA 7408 3.6.1.3 · CIE 9702 17.2.1, 17.2.2, 17.3.1, 17.3.2 · OCR A H556 5.3.2(a), 5.3.2(b), 5.3.3(b)(i) · Edexcel 9PH0 188

Describe how E_k, E_p and the total energy vary with displacement and with time.
Put a number on the total with E = ½kA², and get CIE's E = ½mω²x₀² out of it through ω² = k/m.
Tell light, heavy and critical damping apart by what each does to the motion.

Forced vibrations and resonance AQA 7408 3.6.1.4 · CIE 9702 17.3.3 · OCR A H556 5.3.3(a), 5.3.3(b)(i), 5.3.3(c), 5.3.3(d), 5.3.3(e) · Edexcel 9PH0 186, 189, 190, 191

Separate free vibrations at the natural frequency from forced vibrations at the driving frequency, and state the resonance condition.
Describe how damping reshapes the resonance curve and how the oscillator's phase sits relative to the driver, with mechanical and stationary-wave examples.
For Edexcel, say how a resistive force and the plastic deformation of a ductile metal each take energy out of an oscillation and bring the amplitude down.

Thermal physics

Internal energy and changes of state AQA 7408 3.6.2.1 · CIE 9702 14.1.1, 14.1.2, 16.1.1, 16.1.2, 16.2.2 · OCR A H556 5.1.1(a), 5.1.2(a), 5.1.2(b), 5.1.2(d), 5.1.2(f), 5.1.2(g) · Edexcel 9PH0 147

Describe solids, liquids and gases by the spacing, the ordering and the motion of their particles.
Define internal energy, and describe the two ways of changing it.
State that energy passes from the hotter body to the colder one, and that two bodies at the same temperature are in thermal equilibrium.
Explain why temperature holds still through a change of state.

Specific heat capacity and latent heat AQA 7408 3.6.2.1 · CIE 9702 14.3.1, 14.3.2 · OCR A H556 5.1.3(a), 5.1.3(b)(i), 5.1.3(c), 5.1.3(d)(i) · Edexcel 9PH0 2, 144

Calculate energy transfers with Q = mcΔθ and Q = ml, stage by stage where a problem needs it.
Describe an electrical determination of a specific latent heat, for melting and for boiling, and say how the heat losses are cancelled.

Ideal gases and the gas laws AQA 7408 3.6.2.2 · CIE 9702 14.2.1, 14.2.2, 14.2.3, 14.2.4, 15.1.2, 15.2.1, 15.2.2, 15.2.3 · OCR A H556 5.1.1(b), 5.1.1(c), 5.1.1(d), 5.1.2(e), 5.1.4(a), 5.1.4(d)(i), 5.1.4(g) · Edexcel 9PH0 148, 150

Say what an ideal gas is: one that obeys pV ∝ T at all pressures.
Use the three empirical gas laws, each with its fixed quantity named.
Explain how extrapolating those lines locates absolute zero.
Apply pV = nRT and pV = NkT, choosing moles or molecules to suit the question.
Calculate work done at constant pressure with pΔV, and convert between molar and molecular mass.

The kinetic theory model and its derivation AQA 7408 3.6.2.3 · CIE 9702 15.3.1, 15.3.2 · OCR A H556 5.1.2(c), 5.1.4(b), 5.1.4(c), 5.1.4(e) · Edexcel 9PH0 149

Set the empirical gas laws against the kinetic theory model, with Brownian motion as the evidence for atoms.
List the assumptions, then reproduce the derivation of pV = ⅓Nm(c_rms)² from them.

What temperature means for a gas AQA 7408 3.6.2.3 · CIE 9702 15.3.3, 15.3.4 · OCR A H556 5.1.4(f), 5.1.4(h), 5.1.4(i) · Edexcel 9PH0 152

Use ½m(c_rms)² = 3kT/2 = 3RT/2N_A, and read off what temperature means.

Gravitational fields

The field concept AQA 7408 3.7.1 · CIE 9702 13.1.2, 13.3.3 · OCR A H556 5.4.1(a), 5.4.1(c), 5.4.1(e), 6.2.2(d) · Edexcel 9PH0 108, 174, 179

Define a force field, name the three origins the specification lists, and read a field-line diagram.
Compare gravitational and electrostatic forces, the shared inverse-square structure and the one difference.

Newton's law of gravitation AQA 7408 3.7.2.1, 3.7.2.2 · CIE 9702 13.1.1, 13.2.1, 13.2.2, 13.3.1, 13.3.2 · OCR A H556 5.4.1(b), 5.4.1(d), 5.4.2(a), 5.4.2(b), 5.4.2(c) · Edexcel 9PH0 175, 176, 177

Use Newton's law of gravitation for point masses.
Define g as force per unit mass and use g = F/m.
Use g = GM/r² in a radial field, with r measured from the centre.

Gravitational potential AQA 7408 3.7.2.3 · CIE 9702 13.4.1, 13.4.2, 13.4.3 · OCR A H556 5.4.4(a), 5.4.4(b), 5.4.4(c), 5.4.4(d) · Edexcel 9PH0 178

Define gravitational potential with its zero at infinity, and use ΔW = mΔV.
Use V = −GM/r and explain the significance of the negative sign.
Explain why no work is done moving along an equipotential surface.
Connect the g and V graphs, with g the negative gradient of V and the size of ΔV the area under g against r.

Orbits and satellites AQA 7408 3.7.2.4 · CIE 9702 13.2.3, 13.2.4 · OCR A H556 5.4.3(a), 5.4.3(b), 5.4.3(c), 5.4.3(d), 5.4.3(e), 5.4.4(e) · Edexcel 9PH0 180

State Kepler's three laws, and use the equal-areas law to compare a planet's speed at the two ends of its orbit.
Derive T² ∝ r³ from gravity as the centripetal force.
Find the orbital speed at any radius, and say why lower orbits are faster.
Account for a satellite's kinetic, potential and total energy.
Use escape velocity, and explain why the escaping mass drops out of it.
Describe synchronous, geostationary and low orbits, including the geostationary plane and radius.

Electric fields

Coulomb's law and electric field strength AQA 7408 3.7.3.1, 3.7.3.2 · CIE 9702 18.1.1, 18.1.2, 18.1.3, 18.2.1, 18.2.2, 18.3.1, 18.3.2, 18.4.1 · OCR A H556 6.2.1(a), 6.2.1(b), 6.2.1(c), 6.2.1(d), 6.2.2(a), 6.2.2(b), 6.2.3(a), 6.2.3(c) · Edexcel 9PH0 109, 110, 111, 113

Use Coulomb's law for point charges, with charged spheres acting from their centres.
Use E = F/Q, and the radial field of a point charge.
Derive the uniform field E = V/d from Fd = QΔV, and use it.
Predict the parabolic path of a charge entering a uniform field at right angles.

Electric potential AQA 7408 3.7.3.3 · CIE 9702 18.5.1, 18.5.2, 18.5.3, 18.5.4 · OCR A H556 6.2.4(a), 6.2.4(b), 6.2.4(c), 6.2.4(d), 6.2.4(e) · Edexcel 9PH0 112, 114, 115

Define absolute electric potential with its zero at infinity, and use ΔW = QΔV.
Use the radial potential of a point charge, and read equipotential diagrams.
Translate between the E and V graphs, gradient in one direction and area in the other.

Comparing electric and gravitational fields AQA 7408 3.7.1, 3.7.3.1 · CIE 9702 · OCR A H556 6.2.2(c) · Edexcel 9PH0 179

Pair the gravitational and electric equations, and state the one structural difference between them.
Compare the magnitudes of the two forces between subatomic particles, and interpret the answer.

Capacitance

Capacitors and the dielectric AQA 7408 3.7.4.1, 3.7.4.2 · CIE 9702 19.1.1, 19.1.2 · OCR A H556 6.1.1(a), 6.2.3(b) · Edexcel 9PH0 116

Define capacitance with C = Q/V and use the parallel-plate formula.
Describe how a polar dielectric molecule rotates in the field, and why that raises C.

Energy stored and capacitor combinations AQA 7408 3.7.4.3 · CIE 9702 19.1.3, 19.1.4, 19.2.1, 19.2.2 · OCR A H556 6.1.1(c), 6.1.1(d), 6.1.1(e)(i), 6.1.2(a), 6.1.2(b), 6.1.2(c) · Edexcel 9PH0 117

Find the stored energy from the area under a V against Q graph.
Choose between the three energy forms according to the quantities a question supplies.
For CIE and OCR, derive the series and parallel combination formulas and use them.

Charging and discharging AQA 7408 3.7.4.4 · CIE 9702 19.3.1 · OCR A H556 6.1.1(b), 6.1.3(a)(i) · Edexcel 9PH0 118

Describe charging and discharging as a flow of electrons in the leads, with no charge crossing the gap.
Sketch and explain the Q, V and I against t graphs for discharge.
Sketch and explain the charging graphs, in which the current falls while the charge and pd rise.
Read gradients and areas: current from the magnitude of the Q–t gradient, charge from the I–t area.

The time constant and exponential decay AQA 7408 3.7.4.4 · CIE 9702 19.3.1, 19.3.2, 19.3.3 · OCR A H556 6.1.3(b), 6.1.3(c), 6.1.3(d), 6.1.3(e) · Edexcel 9PH0 118, 120

Calculate the time constant RC and read it from graphs.
Use the discharge and charging equations, and T½ = 0.69RC.
Model a discharge step by step from ΔQ/Δt = −Q/CR, and compare the model with the exponential.
Determine RC from a log-linear plot, as in required practical 9.

Magnetic fields

Magnetic flux density and the force on a wire AQA 7408 3.7.5.1 · CIE 9702 20.1.1, 20.1.2, 20.2.1, 20.2.2, 20.2.3, 20.4.1, 20.4.2, 20.4.3 · OCR A H556 6.3.1(a), 6.3.1(b), 6.3.1(c), 6.3.1(d), 6.3.1(e)(i), 6.3.1(e)(ii), 6.3.1(f) · Edexcel 9PH0 123

Use F = BIl for a wire perpendicular to the field.
Use F = BIl sin θ where the wire lies at an angle θ to the field.
Apply Fleming's left hand rule to find the direction of the force.
Define magnetic flux density and the tesla.
Describe the required-practical measurement of the force with a top-pan balance.

Force on a moving charge AQA 7408 3.7.5.2 · CIE 9702 20.3.1, 20.3.2, 20.3.3, 20.3.4, 20.3.5, 20.3.6 · OCR A H556 6.3.2(a), 6.3.2(b), 6.3.2(c) · Edexcel 9PH0 122, 133, 134

Use F = BQv for a charge moving perpendicular to the field, with the correct direction for either sign.
Explain why a magnetic force can do no work on a moving charge.
Explain why the path is a circle, and derive r = mv/BQ.
Explain the Hall probe and the velocity selector, each as an electric force set against the magnetic one.
Describe the cyclotron, with magnetic steering set against electric acceleration.

Magnetic flux and flux linkage AQA 7408 3.7.5.3 · CIE 9702 20.5.1, 20.5.2, 20.5.3 · OCR A H556 6.3.3(a), 6.3.3(b), 6.3.3(d)(ii) · Edexcel 9PH0 121

Use Φ = BA for an area normal to the field, in webers.
Use flux linkage NΦ, and NΦ = BANcosθ for a rotated coil, with θ to the normal.
Describe the required-practical investigation with a search coil and oscilloscope.

Electromagnetic induction: Faraday and Lenz AQA 7408 3.7.5.4 · CIE 9702 20.5.4, 20.5.5 · OCR A H556 6.3.3(c), 6.3.3(d)(i), 6.3.3(e) · Edexcel 9PH0 124, 126, 127

Use Faraday's law: the induced emf equals the rate of change of flux linkage.
Use Lenz's law for direction, and justify it by energy conservation.
Apply both to a moving conductor and to a uniformly rotating coil.

Alternating currents AQA 7408 3.7.5.5 · CIE 9702 21.1.1, 21.1.2, 21.1.3, 21.1.4 · OCR A H556 4.4.1(b)(ii) · Edexcel 9PH0 128, 129

Define alternating current, and read peak, peak-to-peak and rms values from sinusoidal waveforms.
Use the rms relations and apply them to mains electricity.
Use an oscilloscope to measure voltages, time intervals and frequencies.

Rectification and smoothing CIE 9702 21.2.1, 21.2.2, 21.2.3, 21.2.4

Sketch half-wave and full-wave rectified outputs, and explain how a bridge of four diodes steers both half-cycles the same way through a load.
Explain smoothing with a reservoir capacitor, and how C and the load resistance together set the ripple.

Transformers AQA 7408 3.7.5.6 · OCR A H556 6.3.3(f)(i) · Edexcel 9PH0 125

Explain transformer operation through alternating flux and induced emf.
Use the turns-ratio equation, and say why a transformer needs ac.
Name the four causes of inefficiency, and use the efficiency equation.
Calculate transmission-line power losses, and explain the high-voltage grid.

Nuclear physics

Rutherford scattering and the nuclear model AQA 7408 3.8.1.1 · CIE 9702 11.1.1 · OCR A H556 6.4.1(a), 6.4.1(c) · Edexcel 9PH0 2, 131

Describe the alpha scattering results, and argue from them to a small, massive, positive nucleus.

Alpha, beta and gamma radiation AQA 7408 3.8.1.2 · CIE 9702 11.1.7 · OCR A H556 6.4.3(b)(i), 6.4.3(b)(ii) · Edexcel 9PH0 6, 168, 169

Identify alpha, beta and gamma from a simple absorption experiment, and give the composition, mass and charge of each, both signs of beta included.
Match each radiation to its applications and to the hazard it presents.
Use the inverse-square law for gamma with corrected count rates, as in required practical 12.

Radioactive decay and the decay constant AQA 7408 3.8.1.3 · CIE 9702 23.2.1, 23.2.2, 23.2.3, 23.2.4, 23.2.5, 23.2.6 · OCR A H556 6.4.3(c), 6.4.3(d), 6.4.3(e)(i), 6.4.3(f)(i), 6.4.3(f)(ii) · Edexcel 9PH0 170, 172

Give the experimental evidence that decay is random, and say why an activity is a statistical quantity.
Use λ, A = λN and the exponential decay equations.
Convert a mass into a number of nuclei with molar mass and the Avogadro constant.
Model a decay step by step from ΔN/Δt = −λN, and say why the model runs low and how to fix it.

Half-life and nuclear instability AQA 7408 3.8.1.4 · CIE 9702 11.1.6, 11.1.11 · OCR A H556 6.4.2(h), 6.4.3(a), 6.4.3(g), 6.4.3(h) · Edexcel 9PH0 173

Determine a half-life from decay curves and from log graphs.
Predict the decay mode of a nuclide from its position on the N against Z graph.
Write balanced decay equations, and account for gamma emission from an excited state.

Nuclear radius and density AQA 7408 3.8.1.5 · OCR A H556 6.4.1(c), 6.4.1(f), 6.4.1(g) · Edexcel 9PH0 136

Estimate a nuclear radius from the closest approach of an alpha particle using energy conservation.
Describe radius determination by electron diffraction and sketch the intensity against angle graph.
Use R = R₀A^(1/3) and show that it makes nuclear density the same for every nucleus.

Mass-energy and binding energy AQA 7408 3.8.1.6 · CIE 9702 11.1.12, 23.1.1, 23.1.3, 23.1.4, 23.1.6, 23.1.7 · OCR A H556 6.4.4(a), 6.4.4(b), 6.4.4(d), 6.4.4(e), 6.4.4(f) · Edexcel 9PH0 164, 165, 166

Convert between mass and energy using E = mc² and the 931.5 MeV value of the atomic mass unit.
Calculate a mass difference and a binding energy from nuclear masses.
Compare nuclei fairly using binding energy per nucleon.
Sketch the binding energy per nucleon curve, and mark the fusion and fission release regions on it.

Fission and fusion AQA 7408 3.8.1.6, 3.8.1.7 · CIE 9702 23.1.2, 23.1.5, 23.1.6, 23.1.7 · OCR A H556 6.4.4(b), 6.4.4(g), 6.4.4(j), 6.4.4(k) · Edexcel 9PH0 164, 166, 167, 170

Describe induced fission by thermal neutrons and balance a fission equation.
Explain the chain reaction and the meaning of critical mass.
Calculate the energy released in fission and fusion reactions from nuclear masses.
State the conditions fusion needs, and why the electrostatic repulsion of two positive nuclei sets them.

Nuclear reactors and safety AQA 7408 3.8.1.7, 3.8.1.8 · OCR A H556 6.4.4(h), 6.4.4(i) · Edexcel 9PH0 6, 8

State the functions of the moderator, control rods and coolant, with example materials.
Give the factors behind each of those material choices.
Use the elastic collision model to explain why moderators are made of light nuclei.
Describe the safety features of a reactor, and the handling and storage of radioactive waste.

Electronics

The MOSFET as a switch AQA 7408 3.13.1.1 · CIE 9702 · OCR A H556

Read a MOSFET's drain characteristic, and use the threshold voltage to say whether the channel is open.
Explain how a logic-level gate voltage switches a load, and why the gate itself takes no steady current.

Zener diodes and semiconductor sensors AQA 7408 3.13.1.2, 3.13.1.3, 3.13.1.4 · CIE 9702 20.3.4 · OCR A H556

Use a zener diode and its series resistor to hold an output steady against a wandering supply.
Say what a photodiode and a Hall effect sensor each measure, and choose between a photodiode and an LDR.

Tuned circuits and the Q factor AQA 7408 3.13.3.1 · CIE 9702 · OCR A H556

Find the resonant frequency of an LC circuit, and say what cancels at it.
Tell the series circuit from the parallel one, say which quantity peaks in each, and use the mass on a spring as the analogy for both.
Use Q and the half-power bandwidth together, and predict what extra resistance does to a resonance curve.

Band-pass, band-stop and RC filters AQA 7408 3.13.3.1 · CIE 9702 · OCR A H556

Tell band-pass from band-stop and high-pass from low-pass, and find an RC filter's cut-off.
Say why no filter passes a single frequency, and set a passband against the width of the signal it has to carry.

The ideal op-amp and the comparator AQA 7408 3.13.2.1, 3.13.3.2, 3.13.4.4 · CIE 9702 · OCR A H556

State the properties of the ideal op-amp and use the open-loop relation.
Explain comparator action and saturation, say which input carries the signal, and say what a comparator is for.

Negative feedback amplifiers AQA 7408 3.13.4.1, 3.13.4.2, 3.13.4.4 · CIE 9702 · OCR A H556

Say what negative feedback sacrifices and what it gains.
Use the inverting gain, and explain the virtual earth that produces it.
Use the non-inverting gain, and use the gain-bandwidth product to find a bandwidth.

Summing and difference amplifiers AQA 7408 3.13.4.3 · CIE 9702 · OCR A H556

Use the summing amplifier equation, choosing a separate gain for each input through its own resistor.
Explain how weighted resistors turn a binary number into an analogue voltage.
Use the difference amplifier equation, and explain how it removes interference shared by both inputs.
Spot when saturation or resistor tolerance makes the ideal equations fail.

Combinational logic AQA 7408 3.13.5.1 · CIE 9702 · OCR A H556

Explain why digital signals resist noise, and what regeneration does that amplification cannot.
Write the truth table of each of the six gates without hesitation.
Turn a Boolean expression, or a specification in words, into a gate circuit, the half-adder included.

Flip-flops, counters and clocks AQA 7408 3.13.5.2, 3.13.5.3 · CIE 9702 · OCR A H556

Describe the D-type flip-flop as a one-bit memory, and use counters that halve the frequency at every stage.
Reset a chain early to count modulo n, and tell BCD, up/down and Johnson counters apart.
Read the pulse width, frequency, mark-to-space ratio and duty cycle off an astable's output.

Modulation and PCM AQA 7408 3.13.6.1, 3.13.6.4 · CIE 9702 · OCR A H556

Distinguish baseband from modulated transmission, and say what a carrier achieves.
Find sideband frequencies and bandwidth for AM, and bandwidth for FM.
Weigh AM against FM on bandwidth, noise and cost.
Choose a sampling rate, and follow a signal through pulse-code modulation.

Radio propagation and data security AQA 7408 3.13.6.1, 3.13.6.2, 3.13.6.3 · CIE 9702 · OCR A H556

Tell ground, sky and space waves apart by frequency, mechanism and range.
Explain why a satellite link uses one frequency up and a different one down.
Compare time-division with frequency-division multiplexing, and copper, fibre and radio as media.
Say what encryption and what authentication each protect, and why a checksum is neither.

Engineering physics

Rotational motion and the angular equations AQA 7408 3.11.1.3 · CIE 9702 · OCR A H556

Describe rotation with angular displacement, angular velocity and angular acceleration, in radians.
Solve uniform angular acceleration problems with the four angular equations of motion.

Moment of inertia and rotational kinetic energy AQA 7408 3.11.1.1, 3.11.1.2 · CIE 9702 · OCR A H556

Say what moment of inertia measures and how mass distribution changes it, using values you are given.
Calculate rotational kinetic energy with half I omega squared, including for flywheels storing energy.

Torque and angular acceleration AQA 7408 3.11.1.4 · CIE 9702 · OCR A H556

Calculate torque as Fr and link it to angular acceleration through T = Iα.

Angular momentum and rotational power AQA 7408 3.11.1.5, 3.11.1.6 · CIE 9702 · OCR A H556

Use angular momentum Iω, conserve it when no external torque acts, and explain the classic cases.
Apply angular impulse TΔt = Δ(Iω) when a torque acts for a time.
Find work and power in rotation from W = Tθ and P = Tω.

The first law and its sign convention AQA 7408 3.11.2.1 · CIE 9702 16.1.2, 16.2.1, 16.2.2 · OCR A H556 5.1.2(f)

Apply Q = ΔU + W with AQA's sign convention, W being work done by the gas.

Non-flow processes and p-V diagrams AQA 7408 3.11.2.2, 3.11.2.3 · CIE 9702 · OCR A H556 5.1.4(i)

Handle the four non-flow processes, isothermal, adiabatic, constant pressure and constant volume, knowing which term each one reduces to zero.
Use pV = constant and pV to the gamma = constant for isothermal and reversible adiabatic changes of an ideal gas.
Calculate work from pΔV at constant pressure, and read work as area on a p-V diagram.

Heat engines and their efficiency AQA 7408 3.11.2.4, 3.11.2.5 · CIE 9702 · OCR A H556

Describe the engine cycle and calculate efficiency from W, Q_H and Q_C, and its theoretical ceiling from the kelvin temperatures.
Explain why no heat engine can be 100% efficient, and why the ceiling rises with a hotter source or colder sink.
Describe the four strokes of a petrol and a diesel engine, and map each onto its theoretical cycle.
Read an indicator diagram, take the work per cycle from its area, and say how the real loop differs from the theoretical one.
Audit a real engine with input, indicated, brake and friction power, and with thermal, mechanical and overall efficiency.

Heat pumps and combined heat and power AQA 7408 3.11.2.5, 3.11.2.6 · CIE 9702 · OCR A H556

Treat refrigerators and heat pumps as reversed engines and calculate both coefficients of performance.
Explain how combined heat and power uses the rejected heat without contradicting the second law.

Astrophysics

The astronomical refracting telescope AQA 7408 3.9.1.1

Draw the ray diagram for a refractor in normal adjustment, and say what normal adjustment means.
Use angular magnification both as a ratio of angles and as one focal length over the other.

Reflecting telescopes AQA 7408 3.9.1.2

Draw the Cassegrain arrangement and explain what each mirror contributes.
Weigh reflectors against refractors, including chromatic and spherical aberration.

Telescopes beyond the visible AQA 7408 3.9.1.3

Compare radio, infrared, ultraviolet and X-ray telescopes with optical ones in structure, siting and use.

Resolving power, collecting power and the CCD AQA 7408 3.9.1.4

Use the Rayleigh criterion θ ≈ λ/D, in radians, to compare resolving powers.
Compare collecting powers through diameter squared, and the CCD with the eye.

The apparent magnitude scale AQA 7408 3.9.2.1 · CIE 9702 25.1.1, 25.1.2, 25.1.3, 25.1.4 · Edexcel 9PH0 157

Use the apparent magnitude scale, including the 2.51 brightness ratio per step.

Stellar distances and absolute magnitude AQA 7408 3.9.2.2 · OCR A H556 5.5.3(a), 5.5.3(b), 5.5.3(c) · Edexcel 9PH0 156, 158

Define the parsec, the light year and the astronomical unit, and convert between them.
Use p = 1/d with p in seconds of arc and d in parsecs, and say why the units are part of the equation.
Say what absolute magnitude means without reaching for the equation.
Convert between apparent and absolute magnitude with m − M = 5 log(d/10).

Black-body radiation and spectral classes AQA 7408 3.9.2.3, 3.9.2.4 · CIE 9702 25.2.1, 25.2.2, 25.2.3 · OCR A H556 5.5.2(e), 5.5.2(i), 5.5.2(j), 5.5.2(k) · Edexcel 9PH0 153, 154, 155

Use black-body curves, Stefan's law and Wien's law to find stellar temperatures, powers and radii.
State the assumptions made when treating a star as a black body.
Recall the spectral classes O to M with their colours, temperatures and absorption lines, and explain the Balmer condition.

The HR diagram and the life of Sun-like stars AQA 7408 3.9.2.5 · OCR A H556 5.5.1(a), 5.5.1(b), 5.5.1(c), 5.5.1(d), 5.5.1(e) · Edexcel 9PH0 158, 159, 160

Sketch the HR diagram with temperature running hot-left to cool-right, the vertical axis read as luminosity increasing upward or as the reversed absolute-magnitude scale, and label the main sequence, red giants, supergiants and white dwarfs.
Describe the evolution of a Sun-like star as a path across the diagram, through the red giant and planetary nebula stages to a white dwarf.

Supernovae, neutron stars and black holes AQA 7408 3.9.2.6 · OCR A H556 5.5.1(f), 5.5.1(g) · Edexcel 9PH0 159, 160

Describe the evolution of a massive star through the red supergiant and supernova stages to a neutron star or a black hole.
Explain why a type Ia supernova works as a standard candle, read its light curve, and say what standardises it.
Compare a gamma-ray burst's energy output with the Sun's.
Recall neutron star properties and use the Schwarzschild radius for black holes.

The Doppler effect and red shift AQA 7408 3.9.3.1 · CIE 9702 7.3.1, 7.3.2, 25.3.1, 25.3.2 · OCR A H556 5.5.3(e), 5.5.3(f) · Edexcel 9PH0 161, 162

Use Δf/f = v/c and z = Δλ/λ with the sign of each shift defined, and say where the approximation stops being safe.
Interpret the periodic Doppler shift of a spectroscopic binary seen in the plane of its orbit.

Hubble's law and the Big Bang AQA 7408 3.9.3.2 · CIE 9702 25.3.3, 25.3.4 · OCR A H556 5.5.3(d), 5.5.3(g), 5.5.3(h), 5.5.3(i), 5.5.3(j), 5.5.3(k), 5.5.3(l), 5.5.3(m), 5.5.3(n), 5.5.3(o) · Edexcel 9PH0 162, 163

Use Hubble's law to find distances, and estimate the age of the universe from 1/H.
State the two pieces of Big Bang evidence AQA names, with the reason each counts.
State the Cosmological principle in its three parts, and say what the Big Bang means for space-time.
For OCR, tell the story of the universe from the Big Bang to now, stage by stage, with the reason each stage waited for its temperature.

Quasars AQA 7408 3.9.3.3

Describe the discovery and nature of quasars, and estimate their distances and power outputs from red shift.

Detecting exoplanets AQA 7408 3.9.3.4

Explain why direct exoplanet detection fails, and interpret the radial velocity method and the transit light curve.

Turning points

Cathode rays and the electron gun AQA 7408 3.12.1.1, 3.12.1.2 · CIE 9702 · OCR A H556 · Edexcel 9PH0 132

Describe how cathode rays are produced in a discharge tube.
Explain thermionic emission, and how an electron gun turns it into a beam.
Use eV = ½mv² for an electron accelerated from rest.

The specific charge of the electron AQA 7408 3.12.1.3 · CIE 9702 20.3.6 · OCR A H556 6.3.2(c)

Outline the crossed-fields determination of e/m for the electron.
Compare the electron's specific charge with the hydrogen ion's, and explain why Thomson's result mattered.

Millikan's oil drop experiment AQA 7408 3.12.1.4 · CIE 9702 · OCR A H556

Use the balance condition QV/d = mg for a stationary charged droplet.
Use Stokes' law and terminal speed to find a droplet's radius and mass.
Explain what Millikan's results showed, namely that charge is quantised in units of e.

Corpuscles, waves and Young's fringes AQA 7408 3.12.2.1, 3.12.2.2 · CIE 9702 · OCR A H556 4.4.3(f)

Compare Newton's corpuscular theory with Huygens' wave theory, and say why Newton's was preferred.
Explain the significance of Young's fringes, and why acceptance of the wave theory was delayed.

Electromagnetic waves and the speed of light AQA 7408 3.12.2.3

Say what ε₀ and μ₀ each measure, and use c = 1/√(μ₀ε₀).
Outline Fizeau's and Hertz's measurements, and what each one settled.

Quanta and the photoelectric effect AQA 7408 3.12.2.4 · CIE 9702 22.1.1, 22.1.2 · OCR A H556 4.5.1(a), 4.5.1(b), 4.5.2(b), 4.5.2(e)

Describe the ultraviolet catastrophe and Planck's resolution in terms of quanta.
State the three failures of classical wave theory over photoelectricity, and why Einstein's answer mattered.

Matter waves and electron microscopes AQA 7408 3.12.2.5, 3.12.2.6 · CIE 9702 22.3.1, 22.3.2, 22.3.3, 22.3.4 · OCR A H556 4.5.3(a), 4.5.3(c)

Use de Broglie's λ = h/√(2meV), and predict what happens to a diffraction pattern when the pd changes.
Estimate the pd needed for atomic-scale electron wavelengths.
Outline the TEM and the STM, and give the TEM's practical limitations.

The Michelson-Morley experiment AQA 7408 3.12.3.1, 3.12.3.2 · CIE 9702 · OCR A H556

Describe the principle of the interferometer and the experiment as a search for absolute motion.
Explain the significance of the null result: the speed of light is invariant.
State what an inertial frame is, and the two postulates of special relativity.

Time dilation and muon decay AQA 7408 3.12.3.3 · CIE 9702 · OCR A H556 · Edexcel 9PH0 139

Use the time dilation equation, and identify which observer measures the proper time.
Cite muon decay as the evidence, and run the numbers both ways round.
For Edexcel, say when the relativistic stretching of a particle's lifetime is significant; that board asks for no equation with it.

Length contraction, mass and energy AQA 7408 3.12.3.4, 3.12.3.5 · CIE 9702 · OCR A H556

Use the length contraction equation with proper length.
Describe how mass and kinetic energy vary with speed, and outline Bertozzi's direct test.

Medical physics

Ultrasound imaging AQA 7408 3.10.4.1 · CIE 9702 24.1.1, 24.1.2, 24.1.3, 24.1.4, 24.1.5, 24.1.6 · OCR A H556 6.5.3(a), 6.5.3(b), 6.5.3(c), 6.5.3(d), 6.5.3(e), 6.5.3(f), 6.5.3(g) · Edexcel 9PH0 88, 89

Explain how a piezoelectric transducer generates and detects ultrasound pulses.
Use the pulse-echo technique and d = ct/2 to locate a boundary in tissue.
Say how the duration of the pulse and the wavelength limit the detail a pulse-echo scan can recover.
Distinguish an A-scan from a B-scan.
Use acoustic impedance Z = ρc and the reflection coefficient to explain what reflects where, and why the gel is needed.
For CIE, use I = I₀e^−μx for the attenuation of ultrasound in tissue.
For OCR, find the speed of blood from a Doppler shift with Δf/f = 2v cos θ/c.

MR scanning and the endoscope AQA 7408 3.10.4.2, 3.10.4.3 · CIE 9702 · OCR A H556 · Edexcel 9PH0

Outline the endoscope as total internal reflection put to work.
Describe the principle of the MR scanner: protons precessing in a strong field, a radio-frequency pulse tipping them, and a relaxation time that depends on the tissue.
Weigh MR against CT and ultrasound for a given diagnostic task.

The physics of diagnostic X-rays AQA 7408 3.10.5.1, 3.10.5.3 · CIE 9702 24.2.1, 24.2.2, 24.2.3 · OCR A H556 6.5.1(a), 6.5.1(b), 6.5.1(c), 6.5.1(d), 6.5.1(e)

Describe how an X-ray tube produces X-rays, and find the maximum photon energy from the tube pd.
Explain the continuous and the characteristic parts of the spectrum a tube emits, and what fixes the minimum wavelength.
For OCR, name the four attenuation mechanisms and the energies at which each matters; AQA asks for the differential absorption without the process details.
Use I = I₀e^−μx and the half-value thickness, and explain image contrast including contrast media.

X-ray detectors and CT scanning AQA 7408 3.10.5.2, 3.10.5.4 · CIE 9702 24.2.4 · OCR A H556 6.5.1(f), 6.5.1(g)

Say how an intensifying screen and a flat-panel detector record the beam, and why each can cut the dose.
Explain how a CT scanner builds cross-sectional images, what its narrow beam and detector array are for, and weigh it against a plain X-ray.

Radionuclide imaging and the gamma camera AQA 7408 3.10.6.1, 3.10.6.2, 3.10.6.3 · CIE 9702 24.3.1 · OCR A H556 6.5.2(a), 6.5.2(b), 6.5.2(c)

Explain what a medical tracer is, and why its half-life and emission type must be chosen carefully.
Distinguish physical, biological and effective half-life, and combine them with 1/T_E = 1/T_P + 1/T_B.
Describe how emitted gamma rays are used to build an image of where the tracer went.

PET scanning and radiotherapy AQA 7408 3.10.6.1, 3.10.6.4, 3.10.6.5, 3.10.6.6 · CIE 9702 24.3.2, 24.3.3, 24.3.4, 24.3.5, 24.3.6 · OCR A H556 6.5.2(a), 6.5.2(d), 6.5.2(e)

Explain PET: annihilation into two 511 keV photons, and coincidence detection locating the source.
Say what PET scanning is used to diagnose, and why it is paired with a CT scanner.
Explain how high-energy X-ray beams and beta-emitting implants deliver a dose to a tumour and spare the tissue around it.

The eye as an optical system AQA 7408 3.10.1.1

Trace rays through the eye and say what kind of image lands on the retina.
Explain accommodation as a change of power at fixed image distance, and use 1/u + 1/v = 1/f to find the eye's focal length.
Explain the eye's spectral response and its spatial resolution in terms of rods and cones.

Defects of vision and their correction AQA 7408 3.10.1.2

Find the power in dioptres of the lens that corrects myopia or hypermetropia.
Say what astigmatism is and read the three numbers of its prescription.

The ear and the transmission of sound AQA 7408 3.10.2.1

Describe the transmission of sound through the outer, middle and inner ear.
Explain why the middle ear raises the pressure before the sound reaches the cochlea.

Intensity, loudness and the decibel scale AQA 7408 3.10.2.2, 3.10.2.3

Use I = P/A, and use the intensity level equation in both directions.
Explain why a logarithmic scale is the right one, and say what the dBA scale adds.
Read an equal loudness curve, say how one is produced, and say what damage does to it.

Biological measurement AQA 7408 3.10.3.1

Explain where the p.d. an ECG measures comes from.
Describe how an ECG is obtained, and state what the amplifier has to do.
Name the P wave, QRS complex and T wave and say what each corresponds to.
Explain the relative size and width of each feature of a normal trace.
Read a heart rate off a trace, and say what makes a trace normal.

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