Numbers
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
Circular Motion
- 5 subtopics
- 15 things to know
- A2 Unit 3
What Circular Motion covers
Circular Motion is examined on A2 Unit 3 of WJEC Physics, Oscillations and Nuclei. 66 recall questions across 5 subtopics.
The 5 subtopics
Each one has its own page.
- Angular velocity, period and frequencyRecall questions on Angular velocity, period and frequency.Open →
- Centripetal acceleration and centripetal forceRecall questions on Centripetal acceleration and centripetal force.Open →
- Angular measure, period and frequencyRecall questions on Angular measure, period and frequency.Open →
- Vertical circular motionRecall questions on Vertical circular motion.Open →
- Horizontal circular motion in practiceRecall questions on Horizontal circular motion in practice.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
What does each symbol represent in the equation v = ωr?
Numbers
State the formula for centripetal acceleration in terms of linear speed and radius.
Key term
State the alternative formula for centripetal acceleration in terms of angular velocity.
Numbers
State the formula for centripetal force in terms of mass, speed, and radius.
Key term
Write the equation relating the forces on a ball at the top of a vertical circle to its centripetal acceleration.
Key term
State the equation for the banking angle at which a bend of radius r can be taken at speed v with no friction at all.
Key term
Define the period of rotation.
Key term
Define the frequency of rotation and give its unit.
Key term
Which forces provide the centripetal force on a ball at the top of a vertical circle on the end of a string?
Numbers
An 1100 kg car rounds a bend of radius 45 m at 18 m s⁻¹. Calculate the frictional force needed.
Key term
What is centripetal acceleration?
Key term
Define the radian as a measure of angle.
Key term
Write the equation relating the forces on a ball at the lowest point of a vertical circle to its centripetal acceleration.
Key term
Why is a bend more dangerous when the road surface is wet?
Take Circular Motion further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Centripetal acceleration vs Angular velocity
Centripetal acceleration: the acceleration directed towards the centre of a circular path. Angular velocity: the angle swept out per unit time, measured in radians per second.
Questions from this topic
Each one with the model answer underneath.
- 1
Why does an object moving in a circle at constant speed have a constantly changing velocity?
Model answer
Because velocity is a vector quantity, and although the speed (magnitude) remains constant, the direction of motion is continuously changing.
- 2
What is centripetal acceleration?
Model answer
Centripetal acceleration is the acceleration directed towards the centre of the circle that causes an object to follow a circular path.
- 3
What is centripetal force?
Model answer
Centripetal force is the resultant force acting on an object moving in a circle, directed towards the centre of the circle.
- 4
State the formula used to calculate angular velocity from angular displacement and time.
Model answer
ω = Δθ/Δt, where Δθ is the angular displacement and Δt is the time interval.
- 5
What is the period of circular motion?
Model answer
The period (T) is the time taken for one complete revolution of circular motion.
- 6
Define the frequency of circular motion.
Model answer
Frequency (f) is the number of complete revolutions per unit time.
What is inside Levo
Six ways to work the same material.
Circular Motion revision questions
- What does Circular Motion cover in WJEC A-Level Physics?
- 5 subtopics: angular velocity, period and frequency, centripetal acceleration and centripetal force, angular measure, period and frequency, vertical circular motion and horizontal circular motion in practice. Each one has its own page with questions and model answers.
- How is Circular Motion organised?
- By the WJEC 1420QS specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Circular Motion, 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.