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
Gravitational Fields
- 6 subtopics
- 10 things to know
- Papers 2 and 3
What Gravitational Fields covers
Paper 2 content on gravitation: field strength and the field of a point mass, Newton's law of universal gravitation and the orbits that follow from it, gravitational potential, and the point-by-point comparison with electric fields.
Where it is assessed
Papers 2 and 3
Advanced Physics II, then the general and practical principles paper.
Check the Pearson Edexcel specification ↗The 6 subtopics
Each one has its own page.
- Gravitational fields and gravitational field strengthRecall questions on what a force field is, the definition g = F/m and its unit, why N kg⁻¹ equals m s⁻², and the field lines around a planet and near the surface.Open →
- The field of a point mass and calculations with gRecall questions on the derivation of g = Gm/r², treating a sphere as a point mass, how g varies outside a planet, and finding g at a planet's surface or at orbital radius.Open →
- Newton's law of universal gravitationRecall questions on the law in words and as an equation, what r measures for two spheres, why the force is always attractive, and how it changes with mass and separation.Open →
- Orbital speed, period and geostationary satellitesRecall questions on what supplies the centripetal force, deriving orbital speed and period, the period-radius relationship, and the conditions for a geostationary orbit.Open →
- Gravitational potential and potential energyRecall questions on the definition of gravitational potential, why it is always negative, its value at infinity, equipotential surfaces, and the energy needed to escape.Open →
- Comparing gravitational and electric fieldsRecall questions on where the two field types agree and where they differ, comparing the force laws, definitions and potentials, and why gravity governs the universe though it is far weaker.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Numbers
Why is N kg⁻¹ the same unit as m s⁻², is field strength a vector, and what do field lines near Earth look like?
Numbers
How does g vary with distance from the centre of a planet, outside its surface?
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What is Newton's law of universal gravitation, what does r measure for two spheres, and why is the force always attractive?
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What provides the centripetal force on a satellite, and how does the gravitational force between two masses change if one mass and the separation are both doubled, or if the separation is tripled?
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What relationship links orbital period to orbital radius, how do a satellite's speed and period change in a higher orbit, and does a heavier satellite need to travel faster in a given orbit?
Numbers
What is the equation for gravitational potential in a radial field, is it a scalar or a vector, and what is its value at infinity?
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How is gravitational field strength related to gravitational potential, and what angle do equipotential surfaces make with field lines?
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How do the force laws for two point masses and two point charges compare, and what is the key difference between the fields?
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How do the definitions of gravitational and electric field strength compare, and how do their radial potential equations compare?
Take Gravitational Fields further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Gravitational field strength vs Gravitational potential
Gravitational field strength: force per unit mass. Gravitational potential: work per unit mass from infinity.
Geostationary orbit vs Polar orbit
Geostationary orbit: equatorial orbit matching Earth rotation. Polar orbit: trajectory passing over both poles.
Escape velocity vs Orbital velocity
Escape velocity: minimum launch speed needed to leave a field. Orbital velocity: tangential speed required for a stable path.
Questions from this topic
Each one with the model answer underneath.
- 1
How is a gravitational field defined?
Model answer
It is a region in which a mass experiences a force.
- 2
What is meant by a force field?
Model answer
It is a region of space in which an object experiences a non-contact force because of some property it has, such as its mass.
- 3
What is meant by gravitational field strength?
Model answer
It is the gravitational force acting per unit mass at a point in the field.
- 4
State the defining equation for gravitational field strength and give its unit:
Model answer
g = F/m, measured in N kg⁻¹.
- 5
Why is N kg⁻¹ the same unit as m s⁻²?
Model answer
Since 1 N = 1 kg m s⁻², dividing by kg leaves m s⁻², so the two units are identical.
- 6
Is gravitational field strength a scalar or a vector, and what is its direction?
Model answer
It is a vector, directed towards the centre of the mass producing the field.
What is inside Levo
Six ways to work the same material.
Gravitational Fields revision questions
- What does Gravitational Fields cover in Edexcel A-Level Physics?
- 6 subtopics: gravitational fields and gravitational field strength, the field of a point mass and calculations with g, newton's law of universal gravitation, orbital speed, period and geostationary satellites, gravitational potential and potential energy and comparing gravitational and electric fields. Each one has its own page with questions and model answers.
- How is Gravitational Fields organised?
- By the Edexcel 9PH0 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Gravitational Fields, 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.
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