Numbers
Edexcel A-Level Physics 9PH0
Working as a Physicist
Topic overviewSI base units, derived units and homogeneityUnit prefixes, conversion and order-of-magnitude estimatesResolution, random errors and systematic errorsUncertainty and how uncertainties combineImproving measurements, graphs and evaluating resultsPeer review, publication and scientific integrityRisk, benefit and the role of science in society
Mechanics
Topic overviewThe equations of uniformly accelerated motionDisplacement-time and velocity-time graphsScalars and vectorsResolving vectors and finding resultantsProjectile motionFree-body diagrams and Newton's first and second lawsNewton's third law, mass and weightTerminal velocity and measuring g by free fallLinear momentum and its conservationElastic and inelastic collisions in one dimensionThe moment of a forceCentre of gravity, equilibrium and the principle of momentsWork done by a forceKinetic and gravitational potential energyConservation of energy and dissipationPower, and the equation P = FvEfficiency and wasted energy
Electric Circuits
Topic overviewCurrent, charge and potential differenceResistance, Ohm's law and ohmic behaviourElectrical power and energyKirchhoff's laws: the current and potential difference rulesCombining resistances in series and parallelCircuit calculations, meters and component failureI-V characteristics of conductors, lamps and diodesThermistors, light dependent resistors and resistance changeResistivity and determining it experimentallyCharge carriers, drift velocity and I = nqvAThe potential divider equation and the loading effectSensing circuits with thermistors and light dependent resistorsElectromotive force, internal resistance and lost voltsMeasuring e.m.f. and internal resistance, and cells in combination
Materials
Topic overviewDensity and how it is measuredUpthrust and Archimedes' principleFloating, sinking and upthrust calculationsViscosity, laminar flow and Stokes' lawTerminal velocity of a sphere falling through a liquidMeasuring viscosity by the falling-ball methodHooke's law, stress and strainThe Young modulus and calculations with itDetermining the Young modulus of a wireForce-extension graphs, elastic and plastic deformationStress-strain graphs, ductile and brittle materialsElastic strain energy
Waves and Particle Nature of Light
Topic overviewDescribing a progressive waveThe wave equation and its useLongitudinal and transverse wavesDisplacement-distance and displacement-time graphsMeasuring the speed of sound with an oscilloscopeWavefronts, superposition and phaseCoherence, path difference and phase differenceInterference in practiceStationary waves, nodes and antinodesHarmonics on a stretched stringInvestigating a vibrating string, and air columnsIntensity, the inverse square law and refractive indexRefraction, wave speed and the critical angleTotal internal reflection and measuring refractive indexLenses, ray diagrams and the images they formLens power and the thin lens equationLens calculations and magnificationReflection, transmission and the pulse-echo principlePulse-echo calculations, resolution and ultrasoundPolarisation and diffractionSingle-slit patterns and the diffraction grating equationGrating spectra and measuring wavelengthElectron diffraction and the de Broglie equationde Broglie calculations and wave-particle dualityPhotons and photon energyModels of light and the electronvoltLine spectra and atomic energy levelsThe photoelectric effect and Einstein's equationEvidence for the photon model and photoelectric calculations
Further Mechanics
Topic overviewImpulse and force-time graphsConservation of momentum in two dimensionsInvestigating momentum and analysing collisions on videoElastic and inelastic collisionsKinetic energy, momentum and collision calculationsThe radian, angular displacement and angular velocityAngular velocity, period and frequency of rotationCentripetal accelerationCentripetal force and what provides itVertical loops and centripetal force calculations
Electric and Magnetic Fields
Topic overviewElectric fields and electric field strengthField strength calculations and field diagramsCoulomb's law and the field of a point chargeInverse-square behaviour and combining fieldsElectric potential and field strength as a potential gradientUniform fields between parallel plates, and the potential near a point chargeEquipotentials, field diagrams and work doneCapacitance and the energy stored in a capacitorCapacitor charge and energy calculationsCharging and discharging graphs and the time constantThe exponential decay equations and logarithmic graphsInvestigating capacitor discharge and time-constant calculationsMagnetic flux density, flux and flux linkageForces on currents and moving chargesThe conditions for inducing an e.m.f.Faraday's law and Lenz's lawFlux linkage graphs and induced e.m.f. calculationsAlternating current, peak and r.m.s. valuesOscilloscope traces and alternating current calculations
Nuclear and Particle Physics
Topic overviewNuclide notation, isotopes and the alpha scattering experimentConclusions from alpha scattering and the changing model of the atomThermionic emission and linear acceleratorsThe cyclotron and the radius of a charged particle's pathParticle tracks, conservation laws and why high energies are neededMass-energy equivalence, pair production and annihilationParticle energy units and relativistic lifetimesBaryons, mesons, leptons and quark compositionThe six quarks, antiparticles and fundamental particlesConservation of charge, baryon number and lepton numberQuark changes in beta decay and testing particle equations
Thermodynamics
Topic overviewSpecific heat capacity and specific latent heatMeasuring specific heat capacity and calibrating a thermistorMeasuring specific latent heatInternal energy, temperature and absolute zeroMean kinetic energy and the absolute temperature scaleThe kinetic theory equation and its derivationThe ideal gas equation and molecular kinetic energyBoyle's law and investigating a fixed mass of gasBlack body radiation and Wien's lawThe Stefan-Boltzmann law and stellar calculations
Space
Nuclear Radiation
Topic overviewMass deficit, binding energy and the atomic mass unitBinding energy per nucleon, fission and fusionBackground radiation and the three types of nuclear radiationIonising power, penetration and changes in the nucleusNuclear equations and investigating gamma absorptionActivity, the decay constant and half-lifeDecay graphs and half-life calculations
Gravitational Fields
Oscillations
Topic overviewThe conditions for simple harmonic motionDisplacement, velocity and acceleration in simple harmonic motionThe mass-spring oscillator and the simple pendulumDisplacement, velocity and acceleration graphsReading period, amplitude and speed from oscillation graphsEnergy in an undamped oscillationDamping and where the energy goesFree and forced oscillations and resonanceResonance in practice and determining an unknown mass
Materials
- 12 subtopics
- 16 things to know
- Papers 2 and 3
What Materials covers
Paper 2 content covering density and upthrust, viscous drag and Stokes' law, and the mechanical behaviour of solids: Hooke's law, stress, strain and the Young modulus, force-extension and stress-strain graphs, and the energy stored in a stretched sample. Two core practicals sit inside it: the falling-ball method for viscosity and the Young modulus of a material.
Where it is assessed
Papers 2 and 3
Advanced Physics II, then the general and practical principles paper.
Check the Pearson Edexcel specification ↗The 12 subtopics
Each one has its own page.
- Density and how it is measuredRecall questions on the definition and unit of density, converting from g cm⁻³, and measuring the density of an irregular solid and of a liquid.Open →
- Upthrust and Archimedes' principleRecall questions on what upthrust is, Archimedes' principle, why a pressure difference produces it, and writing it in terms of the fluid density and volume displaced.Open →
- Floating, sinking and upthrust calculationsRecall questions on the condition for floating, the fraction submerged, why a steel ship floats, and finding a volume from apparent loss of weight.Open →
- Viscosity, laminar flow and Stokes' lawRecall questions on what viscosity measures, Stokes' law and the conditions under which it holds, laminar and turbulent flow, and the effect of temperature.Open →
- Terminal velocity of a sphere falling through a liquidRecall questions on the three forces acting, the condition at terminal velocity, the expression that follows, and how terminal velocity depends on radius.Open →
- Measuring viscosity by the falling-ball methodRecall questions on the falling-ball experiment, why the markers are placed below the surface, checking terminal velocity has been reached, and the main uncertainties.Open →
- Hooke's law, stress and strainRecall questions on the statement of Hooke's law, what the spring constant means, tensile and compressive stress, and why strain has no unit.Open →
- The Young modulus and calculations with itRecall questions on the definition and unit of the Young modulus, what a large value means, and how it differs from the stiffness of one sample.Open →
- Determining the Young modulus of a wireRecall questions on the wire experiment, why a long thin wire is chosen, the small initial load, the safety precautions, and which measurement dominates the uncertainty.Open →
- Force-extension graphs, elastic and plastic deformationRecall questions on the limit of proportionality and the elastic limit, elastic against plastic deformation, the yield point, and loading and unloading curves.Open →
- Stress-strain graphs, ductile and brittle materialsRecall questions on the shape of a ductile metal's graph, breaking stress, what the gradient gives, and how a brittle material differs.Open →
- Elastic strain energyRecall questions on the energy stored in a stretched sample, why the factor of a half appears, which area of a graph represents it, and estimating it from a curve.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
What is upthrust?
Process
What does Archimedes' principle state?
Process
How is upthrust written in terms of the density of the fluid and the volume displaced?
Numbers
What is the unit of upthrust, does the upthrust on a fully submerged object change with depth, and what happens to an object whose density equals that of the surrounding fluid?
Numbers
What is the unit of viscosity, what is laminar flow, and how does viscosity change as temperature rises?
Numbers
How does the terminal velocity of a small sphere falling through a liquid depend on its radius?
Process
How can you check experimentally that the ball has actually reached terminal velocity?
Numbers
Why do fine dust particles take so long to settle in still air, and what are the main uncertainties in the falling-ball experiment?
Numbers
What does Hooke's law state, and what does the spring constant k represent?
Key term
What are tensile stress, compressive stress and tensile strain?
Numbers
What is the unit of the Young modulus, what does a large value mean, and how does it differ from stiffness?
Evaluation
Two wires of the same material and diameter carry the same load, but one is twice as long. How do their extensions compare?
Numbers
What does the gradient of a force-extension graph give, what shape is it for a spring obeying Hooke's law, and what is elastic deformation?
Numbers
What does the gradient of a stress-strain graph give, what is breaking stress, and what is the equation for elastic strain energy?
Key term
Which region of a force-extension graph represents the stored elastic strain energy, and what happens to it if the extension is doubled?
Take Materials further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Elastic deformation vs Plastic deformation
Elastic deformation: shape change reversed after force removal. Plastic deformation: permanent shape change after force removal.
Stress vs Strain
Stress: force divided by cross-sectional area. Strain: extension divided by original length.
Stiffness vs Young modulus
Stiffness: force required per unit extension. Young modulus: stress divided by strain.
Questions from this topic
Each one with the model answer underneath.
- 1
What is meant by density?
Model answer
Density is the mass per unit volume of a substance.
- 2
State the equation for density and its SI unit:
Model answer
ρ = m/V, with the unit kg m⁻³.
- 3
A density is quoted as 1 g cm⁻³. What is this in SI units?
Model answer
It is 1 × 10³ kg m⁻³.
- 4
What is the density of fresh water?
Model answer
The density of fresh water is approximately 1.0 × 10³ kg m⁻³.
- 5
A rectangular block of mass 240 g measures 3.0 cm by 4.0 cm by 5.0 cm. What is its density in kg m⁻³?
Model answer
The volume is 60 cm³, so the density is 240/60 = 4.0 g cm⁻³, which is 4.0 × 10³ kg m⁻³.
- 6
How would you determine the density of a small irregularly shaped solid?
Model answer
Find its mass on a balance, then find its volume from the water it displaces in a measuring cylinder or displacement can, and divide mass by volume.
What is inside Levo
Six ways to work the same material.
Materials revision questions
- What does Materials cover in Edexcel A-Level Physics?
- 12 subtopics: density and how it is measured, upthrust and archimedes' principle, floating, sinking and upthrust calculations, viscosity, laminar flow and stokes' law, terminal velocity of a sphere falling through a liquid, measuring viscosity by the falling-ball method, hooke's law, stress and strain, the young modulus and calculations with it, determining the young modulus of a wire, force-extension graphs, elastic and plastic deformation, stress-strain graphs, ductile and brittle materials and elastic strain energy. Each one has its own page with questions and model answers.
- How is Materials organised?
- By the Edexcel 9PH0 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Materials, on a schedule.
Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.
Or £46 a year, about £3.83 a month. Cancel anytime.