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
Working as a Physicist
- 7 subtopics
- 15 things to know
- Papers 1, 2 and 3
What Working as a Physicist covers
Runs through the whole course rather than sitting in one paper: SI units and whether an equation is homogeneous, the difference between random and systematic error, how uncertainties are estimated and combined, and how a result is judged against an accepted value. It also covers peer review and how scientific evidence is used in public decisions.
Where it is assessed
Papers 1, 2 and 3
Practical and mathematical skills, examined on every paper.
Check the Pearson Edexcel specification ↗The 7 subtopics
Each one has its own page.
- SI base units, derived units and homogeneityRecall questions on the six base quantities, how a derived unit is built from them, and why a homogeneity check can rule an equation out but never prove it right.Open →
- Unit prefixes, conversion and order-of-magnitude estimatesRecall questions on the prefixes from pico to tera, converting to SI before substituting, and making an order-of-magnitude estimate to one significant figure.Open →
- Resolution, random errors and systematic errorsRecall questions on the resolution of a rule, calliper and micrometer, the difference between random and systematic error, zero errors, and accuracy against precision.Open →
- Uncertainty and how uncertainties combineRecall questions on estimating uncertainty from an analogue scale, a digital meter and repeated readings, and on adding absolute or percentage uncertainties.Open →
- Improving measurements, graphs and evaluating resultsRecall questions on timing several swings, parallax, light gates, error bars, anomalous results, significant figures, and deciding whether a result agrees with an accepted value.Open →
- Peer review, publication and scientific integrityRecall questions on what a peer reviewer checks, why a method must be reproducible, the two forms of misconduct, and why funding is declared.Open →
- Risk, benefit and the role of science in societyRecall questions on hazard against risk, why perceived risk differs from measured risk, and why science can inform a policy decision but not make it.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Numbers
What are the watt, the pascal and the spring constant expressed in SI base units?
Numbers
What are the base units of density, how is v² = u² + 2as shown to be homogeneous, and what can a homogeneity check not prove?
Process
What multiplying factors are represented by the prefixes pico, nano, micro and milli?
Process
Why is the radian not an SI base unit?
Process
Why should the result of an estimate normally be quoted to one significant figure?
Evaluation
What does an uncertainty tell you, and what is the difference between a repeatable and a reproducible result?
Evaluation
How is the uncertainty in an analogue and in a digital reading estimated, and can readings be precise but not accurate?
Evaluation
How are uncertainties combined when quantities are added, multiplied, or raised to a power?
Numbers
To how many figures should a result be quoted, and why must raw readings match the instrument's resolution?
Evaluation
How do you judge agreement with an accepted value, why is a light gate with an electronic timer better than a stopwatch, and what is the difference between accuracy and precision?
Evaluation
What is the difference between a random error and a systematic error?
Process
Why is peer-reviewed publication not the end of validation, and what misconduct most damages research?
Evaluation
What must accompany a communicated numerical result, and why can science inform a policy decision without making it?
Evaluation
What is the difference between a hazard and a risk, why are risks and benefits weighed against each other, and why must scientists declare who funded their work?
Take Working as a Physicist further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Accuracy vs Precision
Accuracy: closeness to the accepted value. Precision: closeness of repeated readings to each other.
Random uncertainty vs Systematic uncertainty
Random uncertainty: unpredictable variation causing scatter. Systematic uncertainty: consistent bias shifting readings in one direction.
Independent variable vs Dependent variable
Independent variable: quantity deliberately changed. Dependent variable: quantity measured in response.
Questions from this topic
Each one with the model answer underneath.
- 1
What is meant by a base quantity?
Model answer
A base quantity is one of the small set of independently defined physical quantities from which every other physical quantity can be built.
- 2
Which six SI base quantities are used in physics at this level, and what is the SI unit of each?
Model answer
Mass in kilograms (kg), length in metres (m), time in seconds (s), electric current in amperes (A), thermodynamic temperature in kelvin (K) and amount of substance in moles (mol).
- 3
What makes a quantity a derived quantity?
Model answer
A derived quantity is defined by a combination of base quantities, so its unit is a product or quotient of base units.
- 4
What is the newton expressed in SI base units?
Model answer
Since force is mass times acceleration, 1 N = 1 kg m s⁻².
- 5
What is the joule expressed in SI base units?
Model answer
Since work is force times distance, 1 J = 1 kg m² s⁻².
- 6
What is the watt expressed in SI base units?
Model answer
Since power is energy divided by time, 1 W = 1 kg m² s⁻³.
What is inside Levo
Six ways to work the same material.
Working as a Physicist revision questions
- What does Working as a Physicist cover in Edexcel A-Level Physics?
- 7 subtopics: si base units, derived units and homogeneity, unit prefixes, conversion and order-of-magnitude estimates, resolution, random errors and systematic errors, uncertainty and how uncertainties combine, improving measurements, graphs and evaluating results, peer review, publication and scientific integrity and risk, benefit and the role of science in society. Each one has its own page with questions and model answers.
- How is Working as a Physicist organised?
- By the Edexcel 9PH0 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Working as a Physicist, 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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