Process
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
Option B: Medical Physics
- 10 subtopics
- 30 things to know
- A2 Unit 4 Section B
- Medical Physics, one of four A2 unit 4 options
What Option B: Medical Physics covers
Option B: Medical Physics is one of four options on A2 Unit 4 of WJEC Physics, Fields and Options, and learners answer on one of the four. 137 recall questions across 10 subtopics.
Where it is assessed
A2 Unit 4 Section B
Fields and Options, one option of four answered.
Check the WJEC specification ↗The 10 subtopics
Each one has its own page.
- Medical physicsRecall questions on Medical physics.Open →
- Ultrasound imagingRecall questions on Ultrasound imaging.Open →
- Radiation and living tissueRecall questions on Radiation and living tissue.Open →
- X-ray production and beam controlRecall questions on X-ray production and beam control.Open →
- Attenuation and half-value thicknessRecall questions on Attenuation and half-value thickness.Open →
- Radiography, fluoroscopy and CT scanningRecall questions on Radiography, fluoroscopy and CT scanning.Open →
- Acoustic impedance and ultrasound reflectionRecall questions on Acoustic impedance and ultrasound reflection.Open →
- Magnetic resonance imagingRecall questions on Magnetic resonance imaging.Open →
- Absorbed dose, equivalent dose and effective doseRecall questions on Absorbed dose, equivalent dose and effective dose.Open →
- Radionuclide tracers, the gamma camera and PETRecall questions on Radionuclide tracers, the gamma camera and PET.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Process
How does a piezoelectric transducer send and receive ultrasound?
Key term
State the Doppler equation used to study blood flow with an ultrasound probe.
Key term
Explain the origin of the continuous background in an X-ray spectrum.
Key term
Why does X-ray therapy use much more energetic photons than X-ray diagnosis?
Key term
State the attenuation equation for a parallel X-ray beam and define every symbol with its unit.
Key term
Explain how a plain radiograph forms an image of the inside of the body.
Key term
How does an anti-scatter grid improve the quality of a radiograph?
Key term
Why does a boundary between two media of nearly equal acoustic impedance produce only a weak echo?
Key term
Explain why the lungs and a gas-filled bowel are very poor subjects for ultrasound examination.
Key term
State the Larmor equation for a hydrogen nucleus and define each symbol with its unit.
Key term
How does an MRI scanner determine where in the body a signal has come from?
Key term
Why is the main magnet of an MRI scanner usually superconducting?
Key term
State the equation for equivalent dose and name its unit.
Key term
State the equation for effective dose and explain what the tissue weighting factor represents.
Key term
Distinguish between a deterministic and a stochastic effect of ionising radiation.
Key term
Explain the purpose of the collimator on a gamma camera.
Key term
What happens inside the scintillation crystal of a gamma camera?
Key term
Name the three main areas of medicine where physics principles are applied.
Key term
Which type of radiation is most hazardous as an external source, and why?
Key term
Which type of radiation is most hazardous as an internal source, and why?
Key term
What is meant by the attenuation of an X-ray beam?
Key term
What is the principle behind X-ray imaging for visualising internal body structures?
Key term
What is ultrasound?
Key term
Why is ionising radiation nonetheless used in radiotherapy?
Key term
Why must the interior of an X-ray tube be evacuated?
Key term
Explain why the intensity of an X-ray beam falls exponentially with the thickness of absorber.
Key term
Why do bones appear as pale areas on a conventional radiograph?
Key term
Define the acoustic impedance of a medium and give the equation for it.
Key term
What can a tracer study show that a radiograph cannot?
Take Option B: Medical Physics further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Alpha radiation vs Gamma radiation
Alpha radiation: a helium nucleus, strongly ionising but stopped by paper. Gamma radiation: a high-energy photon, weakly ionising but stopped only by thick lead.
An A-scan vs A B-scan
An A-scan: a display of reflected pulses along one line, read as depths. A B-scan: a two-dimensional image built from many lines, each reflection shown as brightness.
Radiotherapy vs Diagnostic imaging
Radiotherapy: the deliberate use of ionising radiation to destroy malignant cells. Diagnostic imaging: the use of radiation to see inside the body, where the dose is minimised.
Questions from this topic
Each one with the model answer underneath.
- 1
What is the primary purpose of medical physics in clinical settings?
Model answer
To apply physics principles to the diagnosis, treatment, and prevention of disease.
- 2
Name the three main areas of medicine where physics principles are applied.
Model answer
Diagnosis, treatment, and prevention of disease.
- 3
What is the principle behind X-ray imaging for visualising internal body structures?
Model answer
X-rays are differentially absorbed by tissues of different densities, creating contrast images of internal structures non-invasively.
- 4
How does ultrasound imaging produce images of internal body structures?
Model answer
It uses high-frequency sound waves that reflect off tissue boundaries, with the echoes processed to create images non-invasively.
- 5
What physical phenomenon does MRI exploit to visualise internal body structures?
Model answer
MRI uses the magnetic properties of hydrogen nuclei (protons) in the body, which align and resonate in strong magnetic fields and radiofrequency pulses.
- 6
How does CT scanning differ from conventional X-ray imaging?
Model answer
CT scanning takes multiple X-ray images from different angles around the body and uses computer processing to create cross-sectional (tomographic) images.
What is inside Levo
Six ways to work the same material.
Option B: Medical Physics revision questions
- What does Option B: Medical Physics cover in WJEC A-Level Physics?
- 10 subtopics: medical physics, ultrasound imaging, radiation and living tissue, x-ray production and beam control, attenuation and half-value thickness, radiography, fluoroscopy and ct scanning, acoustic impedance and ultrasound reflection, magnetic resonance imaging, absorbed dose, equivalent dose and effective dose and radionuclide tracers, the gamma camera and pet. Each one has its own page with questions and model answers.
- How is Option B: Medical Physics organised?
- By the WJEC 1420QS specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Option B: Medical 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.
Or £46 a year, about £3.83 a month. Cancel anytime.