Key term
WJEC A-Level Physics 1420QS
Basic Physics
Kinematics
Dynamics
Energy Concepts
Solids Under Stress
Using Radiation to Investigate Stars
Particles and Nuclear Structure
Topic overviewQuarks, leptons and hadronsThe four interactions and conservation lawsThe first generation of quarks and leptonsAntiparticles and annihilationBaryons, antibaryons and mesonsDeducing quark compositions from chargeBeta decay and quark flavour changeTesting a reaction against the conservation rules
Conduction of Electricity
Resistance
Topic overviewCalculating resistance from resistivityPotential difference, Ohm's law and powerResistivity, temperature and superconductivityThe volt: energy transferred per unit chargeCurrent–voltage characteristics of non-ohmic componentsMeasuring resistance and resistivity in the laboratoryThe heating effect of a current and choosing a power equationThermistors and how a semiconductor's resistance falls with temperatureConductance, conductivity and comparing materials
D.C. Circuits
Topic overviewKirchhoff's laws, and resistors in series and parallelPotential dividers, emf and internal resistanceCells, resistivity, power and energyWorking out currents and potential differences in resistor networksSensor circuits with thermistors and LDRsInternal resistance, power transfer and short-circuit currentAmmeters, voltmeters and their effect on the circuit
The Nature of Waves
Wave Properties
Topic overviewEnergy transfer and the wave equationTransverse and longitudinal waves, path difference and intensityDiffraction and superpositionTwo-source interference and the diffraction gratingStationary wavesHow much a wave spreads at a gap or an obstacleCoherence and the conditions for observable interferenceYoung's double slit and λ = ay/DMeasuring wavelength with a diffraction gratingMeasuring the speed of sound with stationary waves
Refraction of Light
Photons
Topic overviewPhoton energy and the electronvoltThe photoelectric effectStopping potential and the Planck constantThe photoelectric effect and photon energiesLine spectra and energy levelsDemonstrating the photoelectric effectThe electromagnetic spectrum and typical photon energiesElectron diffraction and the de Broglie relationshipRadiation pressure
Lasers
Circular Motion
Vibrations
Topic overviewSimple harmonic motion and its equationsOscillating systems and energyDamping and resonanceThe simple pendulumThe mass–spring oscillatorThe displacement and velocity equationsGraphs of displacement, velocity and accelerationThe energy interchange in simple harmonic motionFree and forced oscillationsLight, heavy and critical damping
Kinetic Theory
Thermal Physics
Topic overviewInternal energy and heatWork, the first law and specific heat capacityThermal equilibrium, temperature and absolute zeroThe internal energy of an ideal monatomic gasWork done by a gas at constant pressureThe p–V diagram and work as an areaSign conventions and special cases of the first lawMeasuring specific heat capacity
Nuclear Decay
Nuclear Energy
Capacitance
Topic overviewCapacitance and the parallel plate capacitorEnergy, combinations and RC circuitsCharging at constant current and measuring capacitanceDielectrics and relative permittivityThe uniform field between capacitor platesEnergy stored in a capacitor and the Q–V graphExponential discharge, the time constant and log graphsCapacitors in series and parallel: charge and potential difference sharing
Electrostatic and Gravitational Fields of Force
Topic overviewElectric and gravitational fields comparedField lines, equipotentials and combining fieldsElectric potential and the work done on a chargeGravitational potential and potential energyAdding potentials and fields from several sourcesEquipotential surfacesComparing the two fields point by point
Orbits and the Wider Universe
Topic overviewKepler's laws and orbital motionThe Doppler effect, dark matter and the expanding universeNewton's law of gravitation applied to orbitsDeriving Kepler's third lawFinding the mass of a central objectGalactic rotation curves and dark matterThe centre of mass of a two-body systemRadial velocity and the Doppler shift of spectral linesHubble's law and the age of the universe
Magnetic Fields
Topic overviewMagnetic fields and field patternsMagnetic flux density and the force on a conductorThe force on a moving charge and its circular pathThe Hall effect and the Hall voltageMagnetic fields due to a current in a wire and in a solenoidForces between current-carrying conductorsCharged particle beams, velocity selectors and accelerators
Electromagnetic Induction
Option A: Alternating CurrentsOption A
Option B: Medical PhysicsOption B
Topic overviewMedical physicsUltrasound imagingRadiation and living tissueX-ray production and beam controlAttenuation and half-value thicknessRadiography, fluoroscopy and CT scanningAcoustic impedance and ultrasound reflectionMagnetic resonance imagingAbsorbed dose, equivalent dose and effective doseRadionuclide tracers, the gamma camera and PET
Option C: The Physics of SportsOption C
Topic overviewCentre of gravity, stability and momentsRestitution, moment of inertia and angular momentumRotational energy, projectiles and the flight of a ballMoments in the muscles and jointsApplying the impulse equation in sportMoment of inertia and angular kinematicsTorque, angular momentum and its conservationRotational energy and energy conservation in sport
Option D: Energy and the EnvironmentOption D
Topic overviewFactors affecting the rate at which the temperature of the Earth risesThe Earth's thermal equilibrium, Wien's law and Stefan's lawRenewable and non-renewable sourcesSolar energy and photovoltaic cellsWind, tidal and hydroelectric powerNuclear fission and fusion as energy sourcesU-values and rates of heat lossFuel cells and how they workFuel cells: benefits, limitations and the hydrogen economyThermal conduction, conductivity and insulation
Mathematical Requirements (Appendix C)
Topic overviewSignificant figures and arithmetic meansUncertainty and how uncertainties combineAlgebraic symbols and proportionalityRearranging and solving equationsSmall angle approximationsTangents and instantaneous rates of changeAreas under curves and numerical methodsReading a tangent on a motion graphStraight-line graphs and y = mx + cWhat a gradient and an intercept representLinearising a relationship to find a constantLog plots of exponential decayChoosing what to plot to find a constantLogarithmic scales and orders of magnitudeWorking with base-ten logarithmsThe shapes of common graphsInverse and root relationships on a graphAreas, volumes and PythagorasGeometry applied to physical situationsSubstituting into physical equationsTrigonometry and right-angled trianglesResolving a force into componentsRadians, arc length and force diagramsRandom processes and translating between representationsMean values and periodic functionsSymbols for approximation and comparison
Basic Physics
- 7 subtopics
- 21 things to know
- AS Unit 1
What Basic Physics covers
Basic Physics is examined on AS Unit 1 of WJEC Physics, Motion, Energy and Matter. 98 recall questions across 7 subtopics.
The 7 subtopics
Each one has its own page.
- Units and quantitiesRecall questions on Units and quantities.Open →
- Scalars, vectors and densityRecall questions on Scalars, vectors and density.Open →
- Moments, centre of gravity and equilibriumRecall questions on Moments, centre of gravity and equilibrium.Open →
- Prefixes, derived units and unit conversionRecall questions on Prefixes, derived units and unit conversion.Open →
- Adding coplanar vectors and the triangle of forcesRecall questions on Adding coplanar vectors and the triangle of forces.Open →
- Resolving forces on an inclined planeRecall questions on Resolving forces on an inclined plane.Open →
- Taking moments: beams, ladders and stabilityRecall questions on beams, ladders and stability.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
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How is the turning effect of a force measured?
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Why does the tension in a washing line become very large as the line is pulled more nearly horizontal?
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Distinguish between the centre of mass of a body and its centre of gravity.
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Name the six base SI units required by the specification, with their symbols.
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What is the difference between a scalar and a vector quantity?
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Give three examples of scalar quantities.
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What is meant by the turning effect of a force?
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Convert an area of 250 cm² into square metres.
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A brick has a volume of 1400 cm³. Express that volume in cubic metres.
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How is the parallelogram rule used to find the resultant of two forces acting at a point?
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A crate rests in equilibrium on a rough slope. State the magnitude and direction of the frictional force acting on it.
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At what angle of slope are the down-slope and perpendicular components of a body's weight equal?
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State two design features that make an object more stable.
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Which base SI unit measures amount of substance?
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Give three examples of vector quantities.
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Define the moment of a force about a point.
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Why is a length conversion factor squared for an area and cubed for a volume?
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How is the resultant of two vectors found by placing them head to tail?
Numbers
An 8.0 kg sledge slides down a frictionless slope inclined at 15° to the horizontal. Calculate its acceleration, taking g as 9.81 m s⁻².
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Explain, in terms of the line of action of the weight, why a tilted object rights itself instead of toppling.
Take Basic Physics further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
The moment of a force vs The principle of moments
The moment of a force: the turning effect it produces about a point, the force multiplied by the perpendicular distance to that point. The principle of moments: the rule that for a body in equilibrium the total clockwise turning effect about any point equals the total anticlockwise one.
The centre of gravity vs The line of action
The centre of gravity: the single point at which the whole weight of a body may be taken to act. The line of action: the straight path along which a force acts, extended in both directions.
The triangle of forces vs The normal contact force
The triangle of forces: the rule that three coplanar forces in equilibrium can be drawn head to tail as a closed figure. The normal contact force: the push a surface exerts on a body at right angles to that surface.
Questions from this topic
Each one with the model answer underneath.
- 1
Name the six base SI units required by the specification, with their symbols.
Model answer
The kilogram (kg), metre (m), second (s), ampere (A), mole (mol) and kelvin (K).
- 2
Which base SI unit measures amount of substance?
Model answer
The mole (mol).
- 3
Which base SI unit measures thermodynamic temperature?
Model answer
The kelvin (K).
- 4
Express the newton in terms of base SI units.
Model answer
Since F = ma, the newton is kg m s⁻².
- 5
Express the joule in terms of base SI units.
Model answer
Since work is force times distance, the joule is kg m² s⁻².
- 6
Express the watt in terms of base SI units.
Model answer
Since power is energy per unit time, the watt is kg m² s⁻³.
What is inside Levo
Six ways to work the same material.
Basic Physics revision questions
- What does Basic Physics cover in WJEC A-Level Physics?
- 7 subtopics: units and quantities, scalars, vectors and density, moments, centre of gravity and equilibrium, prefixes, derived units and unit conversion, adding coplanar vectors and the triangle of forces, resolving forces on an inclined plane and taking moments: beams, ladders and stability. Each one has its own page with questions and model answers.
- How is Basic Physics organised?
- By the WJEC 1420QS specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Basic Physics, 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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