AQA A-Level Physics

Last Accessed

Recently visited lessons will appear here for quick access.Start exploring your first lesson today!

Compulsory Content

3.1 - Measurements and Their Errors

3.1.1 - Use of SI Units and Their PrefixesA physical answer needs a value and a unit. Learn how base units combine, how prefixes change a number's scale, and how to convert energy units without changing the physical quantity.
3.1.2 - Limitation of Physical MeasurementsA measurement is an estimate supported by evidence, not an exact truth. Learn to diagnose errors, assign realistic uncertainties, carry them through calculations and graphs, and decide which experimental improvement will matter most.
3.1.3 - Estimation of Physical QuantitiesEstimation uses approximate inputs and a physical model to predict a useful scale. Learn to state reasonable assumptions, keep powers of ten under control, and use a rough answer to test whether a detailed calculation makes sense.

3.2 - Particles and Radiation / 3.2.1 - Particles

3.2.1.1 - Constituents of the AtomAn atom’s nuclear composition determines its element and isotope. Use particle charges and masses to read nuclide notation, distinguish an atom from an ion, and calculate charge per unit mass.
3.2.1.2 - Stable and Unstable NucleiIn nuclei containing several protons, those protons are packed closely together. Since like charges repel, there must be something powerful enough to overcome this electrostatic repulsion and hold the nucleus together. In this lesson you will learn about the strong nuclear force, understand why s...
3.2.1.3 - Particles, Antiparticles and PhotonsElectromagnetic radiation can be described as photons, and the same energy ideas explain how matter and antimatter can be destroyed or created. In this lesson you will use the photon model, compare particles with their antiparticles, and link annihilation and pair production through conservation...
3.2.1.4 - Particle InteractionsWhen particles attract, repel, or change identity, physicists describe the process as an interaction. This lesson focuses on the four fundamental interactions, the idea of exchange particles, and the simple electromagnetic and weak-interaction diagrams you need to recognise for A-Level Physics.
3.2.1.5 - Classification of ParticlesThe subatomic world contains a rich zoo of particles discovered through cosmic ray experiments and high-energy accelerator collisions. To make sense of this diversity, physicists classify particles into groups based on the fundamental interactions they experience. In this lesson you will learn th...
3.2.1.6 - Quarks and AntiquarksThe hadrons in this part of the course are not fundamental particles. They are made from quarks and antiquarks, and their charge, baryon number, and strangeness can be found by adding the properties of those constituent particles. In this lesson you will use only the quarks named in the specifica...
3.2.1.7 - Applications of Conservation LawsConservation laws can rule out a proposed particle reaction or determine a missing particle. Apply the independent charge, baryon, lepton and strangeness checks, then include energy and momentum and explain the quark changes in beta decay.

3.2 - Particles and Radiation / 3.2.2 - Electromagnetic Radiation and Quantum Phenomena

3.2.2.1 - The Photoelectric EffectLight can release electrons from a metal surface, but only when each photon has enough energy. The observations distinguish the energy of one photon from the rate at which photons arrive, and lead to a measurable energy balance.
3.2.2.2 - Collisions of Electrons with AtomsA collision can leave an atom excited or can remove an electron completely. Tracking where the incident electron’s energy goes explains the thresholds for these processes and the production of visible light in a fluorescent tube.
3.2.2.3 - Energy Levels and Photon EmissionAtomic spectra contain lines at particular wavelengths because atoms can change their energy only by allowed amounts. Energy-level diagrams let you connect each transition to the energy, frequency and wavelength of its photon.
3.2.2.4 - Wave-Particle DualityPhotoemission reveals the particle-like energy transfer of light, while electron diffraction reveals wave behaviour in matter. The de Broglie relation connects a particle’s momentum to its wavelength and makes a testable prediction about diffraction.

3.3 - Waves / 3.3.1 - Progressive and Stationary Waves

3.3.1.1 - Progressive WavesTrack the motion of the medium separately from the motion of the wave. Use space and time graphs to connect amplitude, wavelength, period, speed and phase, then apply the same reasoning to a sound-speed measurement.
3.3.1.2 - Longitudinal and Transverse WavesWaves can be classified by how the oscillations are arranged relative to the direction of energy transfer. That single idea explains the difference between sound waves, electromagnetic waves, and waves on a string, and it also explains why polarisation is such strong evidence for the nature of tr...
3.3.1.3 - Superposition and Stationary WavesWhen two waves overlap, they do not stop being waves. They pass through each other, and at every point the displacements combine. That simple rule explains the formation of stationary waves on strings, with microwaves, and with sound, and it leads directly to the harmonic patterns and frequency e...
RP01 - Stationary Waves on a StringInvestigate how the first-harmonic frequency depends separately on vibrating length, tension and mass per unit length. Recognise the mode, measure a repeatable resonance, analyse all the data and test the model with justified uncertainties.

3.3 - Waves / 3.3.2 - Refraction, Diffraction and Interference

3.3.2.1 - InterferenceInterference shows what happens when waves overlap. In light, it produces the bright and dark fringes of Young's double-slit experiment; in sound and other electromagnetic waves, it produces alternating maxima and minima of intensity. In this lesson you will learn the conditions for interference,...
3.3.2.2 - DiffractionWhen light meets a narrow slit or a regularly spaced set of slits, it does not simply continue as one straight beam. It spreads, interferes with itself, and produces patterns that reveal wavelength and structure. In this lesson you will focus on the appearance of single-slit diffraction patterns,...
RP02 - Interference EffectsUse Young’s double slit and a normally illuminated transmission grating to measure laser wavelength. Choose measurable spans, convert screen geometry correctly and compare results using their uncertainties.
3.3.2.3 - Refraction at a Plane SurfaceWhen light crosses a boundary between two transparent substances, its speed changes. That change of speed changes the direction of travel unless the ray arrives along the normal. In this lesson you will connect ray diagrams to refractive index, Snell's law, total internal reflection, and the way...

3.4 - Mechanics and Materials / 3.4.1 - Force, Energy and Momentum

3.4.1.1 - Scalars and VectorsDescribe magnitude and direction, build resultants, resolve forces and test equilibrium. The same vector methods apply to displacement, velocity and force, but a force diagram must represent the actual forces on one object.
3.4.1.2 - MomentsUse perpendicular distances to calculate turning effects, locate weight at the centre of mass, and distinguish balanced forces from balanced moments.
3.4.1.3 - Motion Along a Straight LineDescribe straight-line motion using signed quantities, graph gradients and areas, then apply constant-acceleration equations to journeys, free fall and bouncing balls.
RP03 - Determination of g by Free FallDetermine gravitational acceleration from measured fall distances and electronic timing. Choose a graph that matches the start of timing, then use scatter, instrument uncertainty and systematic effects to judge the result.
3.4.1.4 - Projectile MotionResolve a projectile into simultaneous horizontal and vertical motions, then examine how drag, lift and friction change motion and limit speed.
3.4.1.5 - Newton's Laws of MotionChoose a body or system, identify its external forces and use Newton's laws to explain its motion. Learn why interaction pairs differ from balanced forces, how to test the second law, and how the same force equations describe towing, lifts and terminal motion.
3.4.1.6 - MomentumMomentum tracks direction as well as motion. Use signed changes and graph areas to analyse impacts, test when a system conserves momentum, and distinguish that conservation law from the changes in kinetic energy during collisions and explosions.
3.4.1.7 - Work, Energy and PowerWork measures energy transferred by a force; power measures the rate of that transfer. Resolve forces along displacement, use signed graph areas for variable forces, distinguish instantaneous from average power, and measure a motor’s efficiency with realistic uncertainties.
3.4.1.8 - Conservation of EnergyEnergy conservation lets you compare initial and final states without finding the motion at every instant. Track gravitational and kinetic energy carefully, include work by resistance over the actual path, and use the result to judge speeds, stopping distances and realistic energy estimates.

3.4 - Mechanics and Materials / 3.4.2 - Materials

3.4.2.1 - Bulk Properties of SolidsA material can be stiff, strong or able to deform without breaking: these are different properties. Use density, force–extension and stress–strain relationships to compare solids, calculate energy transfers and explain why a useful engineering material sometimes needs to change shape permanently.
3.4.2.2 - The Young ModulusA thick wire is harder to stretch than a thin wire of the same material. The Young modulus separates the material's stiffness from the sample's dimensions. Learn to connect stress–strain gradients, wire calculations and the measurements needed to determine this property.
RP04 - Determination of the Young ModulusDetermine the Young modulus by loading a wire, measuring small extensions and interpreting a graph. This lesson develops the measurement choices, uncertainty analysis and validity checks behind required practical 4. Written planning prepares you for practical work; performing it safely and indepe...

3.5 - Electricity / 3.5.1 - Current Electricity

3.5.1.1 - Basics of ElectricityCurrent measures charge flow, potential difference measures energy per charge, and resistance relates the two. Use these definitions to explain what a circuit transfers and to choose the right quantities in a calculation.
3.5.1.2 - Current-Voltage CharacteristicsA characteristic graph shows the operating current and pd of a component. Read the axes before interpreting resistance, then connect each curve to temperature, direction of conduction and how the measurements are made.
3.5.1.3 - ResistivitySeparate a material’s resistivity from the resistance of a particular wire. Use geometry and graphs to measure it, then explain the different temperature responses of metals, thermistors and superconductors.
RP05 - Determination of Wire ResistivityDetermine a wire’s resistivity by combining its diameter with a resistance–length graph. Plan measurements that test the uniform-wire model, then quantify what the uncertainty permits you to conclude.
3.5.1.4 - CircuitsUse charge and energy conservation to recognise series and parallel connections, simplify resistor networks and check their currents, pds and powers. The connections between nodes determine the physics, not the way a circuit is drawn.
3.5.1.5 - Potential DividerA potential divider supplies a fraction of a source pd. Derive that fraction, choose sensor positions for the required response, and check how a connected load changes the output.
3.5.1.6 - Electromotive Force and Internal ResistanceA real cell transfers energy both to the external circuit and within itself. Use emf, terminal pd and internal resistance to calculate that division and interpret the change in voltage when the load changes.
RP06 - EMF and Internal ResistanceMeasure a cell’s terminal pd at different currents to determine emf and internal resistance. Use a controlled discharge, a consistent graph and an uncertainty estimate to test whether one pair of cell parameters describes the results.

3.6 - Further Mechanics and Thermal Physics / 3.6.1 - Periodic Motion

3.6.1.1 - Circular MotionA constant speed can hide a changing velocity. Use radians to describe rotation, then identify the real forces whose inward resultant bends the path.
3.6.1.2 - Simple Harmonic MotionConnect the restoring acceleration of an oscillator to its displacement, speed and time graphs. Keep signed quantities separate from magnitudes and use the starting position to choose the phase.
3.6.1.3 - Simple Harmonic SystemsDerive the periods of spring and pendulum oscillators from their restoring forces, track their energy, and identify where ideal SHM stops being a useful approximation.
RP07 - Simple Harmonic MotionInvestigate how period depends on pendulum length and hanging mass. Measure complete cycles, test the predicted relationships and use gradients with realistic uncertainties to determine g and spring stiffness.
3.6.1.4 - Forced Vibrations and ResonanceDistinguish a free decay from a sustained forced oscillation. Explain resonance through energy transfer, interpret amplitude-frequency curves, and use damping to control unwanted motion.

3.6 - Further Mechanics and Thermal Physics / 3.6.2 - Thermal Physics

3.6.2.1 - Thermal Energy TransferFollow energy through heating, changes of state and flowing fluids. Distinguish temperature from internal energy, choose the right energy balance, and evaluate measurements of specific heat capacity and latent heat.
3.6.2.2 - Ideal GasesUse measured gas-law relationships to connect pressure, volume, temperature and amount of gas. Convert between molecular and molar descriptions, recognise the limits of the ideal model, and calculate work during expansion.
RP08 - Boyle's Law and Charles's LawPlan and analyse the two gas-law investigations in required practical 8. Control the gas sample, connect force balance to pressure, test proportionality with graphs, and judge offsets and uncertainty before interpreting an extrapolation.
3.6.2.3 - Molecular Kinetic Theory ModelExplain gas pressure using molecular momentum transfers, derive the kinetic-theory equation, and connect molecular motion to temperature. Use the model carefully: mean square speed is not the square of mean speed, and translational energy is not every possible internal-energy contribution.

3.7 - Fields and Their Consequences / 3.7.2 - Gravitational Fields

3.7.2.1 - Newton's Law of GravitationNewton’s law connects the attractive force between masses to their masses and separation. Learn when the point-mass model applies, estimate the scale of gravity and use force measurements to infer unknown quantities.
3.7.2.2 - Gravitational Field StrengthGravitational field strength measures force per kilogram. Connect its vector definition to the inverse-square field outside a spherical planet, and decide when a uniform-field approximation is accurate enough.
3.7.2.3 - Gravitational PotentialGravitational potential describes energy per kilogram relative to a chosen zero. Use it to calculate work, interpret equipotentials and connect a potential graph to the magnitude and direction of the gravitational field.
3.7.2.4 - Orbits of Planets and SatellitesUse gravity as the centripetal force to derive circular-orbit speed and period. Track kinetic, potential and total energy to explain orbital changes and escape, then select an orbit suitable for a satellite’s purpose.

3.7 - Fields and Their Consequences / 3.7.3 - Electric Fields

3.7.3.1 - Coulomb's LawUse Coulomb's law to calculate interactions between charges, decide their directions, and test whether a point-charge model is appropriate. Then compare electric and gravitational forces for subatomic particles without confusing force magnitude with charge sign.
3.7.3.2 - Electric Field StrengthDescribe electric fields using vectors and field lines, calculate uniform and radial fields, and predict the motion of a charged particle between plates. Use a simple potential-mapping method to connect a measured pattern with the direction and strength of the field.
3.7.3.3 - Electric PotentialUse electric potential to track energy transfers and connect potential differences with electric field strength. Distinguish signed work from energy change, read gradients and areas on graphs, and explain why zero field and zero potential are different statements.

3.7 - Fields and Their Consequences / 3.7.4 - Capacitance

3.7.4.1 - CapacitanceA capacitor separates charge without allowing electrons to cross its insulating gap. Learn what its capacitance measures, how charge–voltage data reveal it, and how to calculate charge and charging time.
3.7.4.2 - Parallel Plate CapacitorRelate capacitance to plate geometry and dielectric material, explain molecular polarisation, and distinguish a capacitor connected to a battery from one isolated after charging.
3.7.4.3 - Energy Stored by a CapacitorDerive stored energy from the charge–pd relationship, choose an appropriate energy equation, and account for energy transferred during charging or a partial discharge.
3.7.4.4 - Capacitor Charge and DischargeExplain how resistor–capacitor circuits change with time, use charging and discharging equations, and determine time constants from curve shape, tangents and logarithmic plots.
RP09 - Capacitor Charge and DischargeInvestigate capacitor charging and discharging, turn voltage readings into log-linear plots, and determine the time constant with justified uncertainty. RP09 is the course label for AQA required practical 9.

3.7 - Fields and Their Consequences / 3.7.5 - Magnetic Fields

3.7.5.1 - Magnetic Flux DensityA current-carrying wire can experience a force in an external magnetic field. The field strength, current, active wire length and orientation determine that force. This lesson separates its magnitude from its direction, then uses the force to measure a field or support a load.
RP10 - Force on a Current-Carrying WireRequired practical 10 investigates how the force on a wire depends on magnetic flux density, current and active wire length using a top-pan balance. The wire and magnets must be supported independently, so the balance reveals the magnetic reaction force. A useful investigation controls geometry,...
3.7.5.2 - Moving Charges in a Magnetic FieldA magnetic field can change a charged particle's direction without changing its speed. Begin with the force on one moving charge, use its sign to find the direction, then combine magnetic force with circular motion to understand a cyclotron.
3.7.5.3 - Magnetic Flux and Flux LinkageFlux describes a magnetic field passing through an area. Flux linkage also counts how many turns of a coil share that flux. Both change when a coil rotates, even if the field strength stays constant.
3.7.5.4 - Electromagnetic InductionUse observations, signed flux changes and energy conservation to explain induction, then calculate the emf produced by moving rods and rotating coils.
RP11 - Magnetic Flux Linkage with a Search CoilInvestigate the cosine dependence of flux linkage using a stationary search coil in an alternating field, then evaluate calibration, controlled measurements and graph uncertainty.
3.7.5.5 - Alternating CurrentsDistinguish the period, peak and rms values of a sinusoidal signal, use rms to calculate resistor heating, and read voltage and time scales on an oscilloscope.
3.7.5.6 - The Operation of a TransformerDerive the transformer ratio from shared changing flux, connect current to power and efficiency, and evaluate core losses and high-voltage transmission.

3.8 - Nuclear Physics / 3.8.1 - Radioactivity and Nuclear Energy

3.8.1.1 - Rutherford Scattering (A-level only)Alpha scattering reveals atomic structure indirectly: the pattern of deflections tests how charge and mass are distributed. Learn how the apparatus made that evidence interpretable, why the nuclear model replaced diffuse positive charge, and what scattering alone could not establish.
3.8.1.2 - Alpha, Beta and Gamma RadiationDifferent nuclear radiations deposit energy and penetrate matter differently. Use these properties to identify a source, explain shielding and thickness control, and investigate how the count rate from a gamma source changes with distance.
RP12 - Inverse-Square Law for Gamma RadiationTest how gamma count rate changes with distance, allowing for background radiation and the hidden source–detector offset. Use a linearised graph and counting uncertainties to decide where the inverse-square model is supported. RP12 is this course's local label for AQA required practical 12.
3.8.1.3 - Radioactive DecayA single nucleus has an unpredictable decay time, but a large population has a predictable statistical trend. Connect constant decay probability to exponential decay, half-life and activity, then use counts, graphs and isotope mass to make quantitative decisions.
3.8.1.4 - Nuclear InstabilityA nucleus can change its neutron–proton balance or lose excitation energy. Use the neutron-number graph and conservation equations to track decay, read gamma transitions, and explain why technetium-99m is useful for medical diagnosis.
3.8.1.5 - Nuclear RadiusNuclear radii are only a few femtometres. Use electrostatic energy to set an upper limit on nuclear size, interpret electron-diffraction evidence, and connect the measured radius law to the approximately constant density of nuclear matter.
3.8.1.6 - Mass and EnergyA bound nucleus has less rest mass than its separated nucleons. Learn to turn that mass difference into binding energy, account for every particle in fission and fusion, and use the binding-energy curve to judge which reactions can release energy.
3.8.1.7 - Induced FissionA thermal reactor sustains fission by managing what happens to its neutrons. Follow neutron absorption through successive fission generations, then distinguish the roles and material choices of moderator, control rods and coolant.
3.8.1.8 - Safety AspectsReactor safety depends on controlling both the fission chain and the radiation and heat that remain afterwards. Connect fuel handling, shielding, shutdown and waste storage to the hazards they reduce, then weigh those protections against the benefits and remaining risks of nuclear power.

Optional Sections (your school picks one)

3.9 - Astrophysics (Option A) / 3.9.1 - Telescopes

3.9.1.1 - Two-Lens Astronomical TelescopesA two-lens telescope forms a real image of a distant object and lets the eye view it at a larger angle. Trace that process through the focal planes, then connect the ray geometry to lens separation and angular magnification.
3.9.1.2 - Reflecting TelescopesMirrors can collect light over a large aperture without the colour separation produced by a simple lens. Follow the Cassegrain light path, distinguish chromatic from spherical aberration, and use those differences to justify telescope designs.
3.9.1.3 - Radio, Infrared, Ultraviolet and X-ray TelescopesRadiation outside visible light reveals cool dust, hot gas and energetic sources that an optical view can miss. A telescope's collecting surface, detector and location must suit both the wavelength and the way that radiation interacts with matter.
3.9.1.4 - Telescope Diameter and DetectorsA telescope must collect enough photons and separate the detail of interest; its detector must then record the available information. Use area ratios and the diffraction limit to distinguish these requirements, and compare the eye with a CCD.

3.9 - Astrophysics (Option A) / 3.9.2 - Classification of Stars

3.9.2.1 - Classification by LuminosityA star can look faint because it emits little power, because it is far away, or both. Separate those possibilities by distinguishing luminosity from received intensity, then use apparent magnitude to compare the light that reaches us.
3.9.2.2 - Absolute Magnitude and DistanceAbsolute magnitude compares stars at a fixed distance. Use the geometry of parallax to understand the parsec, then combine independent distance measurements with the magnitude scale to infer and check intrinsic stellar brightness.
3.9.2.3 - Stellar Temperature and Black-Body RadiationThe shape of a stellar spectrum reveals temperature; its total power also depends on surface area. Combine Wien’s law, Stefan’s law and geometrical spreading to infer stellar properties, while keeping emitted power separate from the intensity measured at Earth.
3.9.2.4 - Stellar Spectral ClassesAbsorption lines reveal the states of atoms in a stellar atmosphere. Use their patterns to classify stars by temperature, and explain why strong hydrogen Balmer lines identify an intermediate temperature rather than the hottest stars or the most hydrogen.
3.9.2.5 - The Hertzsprung–Russell DiagramAn HR diagram separates surface temperature from intrinsic brightness. Learn to read its scales, explain the main stellar groups and trace a Sun-like star’s evolution without mistaking the main sequence for a single path through time.
3.9.2.6 - Supernovae, Neutron Stars and Black HolesStellar explosions connect the physics of compact remnants with measurements of the expanding Universe. Distinguish core collapse from Type Ia explosions, use a light curve as distance evidence, and calculate neutron-star densities and black-hole horizon radii.

3.9 - Astrophysics (Option A) / 3.9.3 - Cosmology

3.9.3.1 - Doppler EffectA shifted spectral line measures motion along the line of sight. Use optical and radio lines to calculate that motion, then explain the changing spectra of binary stars and distinguish small Doppler shifts from cosmological redshift.
3.9.3.2 - Hubble's LawThe relation between galaxy recession speed and distance gives a measure of cosmic expansion and an approximate age. Connect that evidence with the microwave background and the primordial hydrogen–helium abundance.
3.9.3.3 - QuasarsQuasars look compact but can outshine their host galaxies. Follow the evidence from radio discovery and optical redshift to distance, power output and an active supermassive black hole.
3.9.3.4 - Detection of ExoplanetsAn exoplanet can reveal itself through the motion and brightness of its host star. Interpret radial-velocity and transit signals, then decide what they establish about orbital period, mass, radius and density.

3.10 - Medical Physics (Option B) / 3.10.2 - Physics of the Ear

3.10.2.1 - Ear as a Sound Detection SystemThe ear transfers pressure variations in air into motion of cochlear fluid and finally into electrical signals. Follow the transfer of energy, the increase in pressure and the position-dependent response that retains information about frequency.
3.10.2.2 - Sensitivity and Frequency ResponseIntensity measures energy transfer; decibels express intensity ratios; equal-loudness curves describe perception. Keeping these three meanings separate lets you calculate sound levels and interpret the frequency response of hearing.
3.10.2.3 - Defects of HearingHearing loss changes the sound levels needed for detection and equal loudness. Compare age-related deterioration and noise injury using measured frequency patterns, without assuming that a graph uniquely identifies a cause.

3.10 - Medical Physics (Option B) / 3.10.4 - Non-Ionising Imaging

3.10.4.1 - Ultrasound ImagingAn ultrasound scanner sends short sound pulses into tissue and measures the echoes. Follow the energy conversions, calculate reflection and depth, and explain how the same signals become an A-scan trace or a B-scan image.
3.10.4.2 - Fibre Optics and EndoscopyOptical fibres guide visible light into and out of the body. Trace the complete optical path through a flexible fibre endoscope, explain which information each bundle must preserve, and relate fibre design to image quality.
3.10.4.3 - Magnetic Resonance ScannerMagnetic resonance imaging uses strong magnetic fields and radio-frequency signals from hydrogen nuclei to build a cross-sectional image. Separate the roles of the main magnet, gradient coils, RF transmitter, receiver and computer.

3.10 - Medical Physics (Option B) / 3.10.5 - X-Ray Imaging

3.10.5.1 - The Physics of Diagnostic X-raysAn X-ray tube converts the energy of accelerated electrons into radiation and heat. Learn how its spectrum is produced, then connect the tube controls and imaging geometry to sharpness, contrast and absorbed dose.
3.10.5.2 - Image Detection and EnhancementAn X-ray image starts as a pattern of transmitted intensities. Follow how film, flat-panel detectors and image intensifiers turn that pattern into a visible image, and how a contrast medium changes the pattern before it reaches the detector.
3.10.5.3 - Absorption of X-raysAttenuation removes photons from the primary X-ray beam by absorption and scattering. Build the exponential model, use its coefficients and half-value thickness, then apply it to layers of tissue and the contrast of a radiograph.
3.10.5.4 - CT ScannerA projection X-ray superimposes structures along each beam path. Computed tomography combines transmission measurements from many angles to reconstruct a cross-sectional map of attenuation, separating structures that overlap in a single view.

3.10 - Medical Physics (Option B) / 3.10.6 - Radionuclide Imaging and Therapy

3.10.6.1 - Imaging TechniquesA radioactive tracer makes the distribution or behaviour of a substance visible. Learn how tracer chemistry, nuclear properties and detector geometry work together, from a hospital technetium generator to PET image reconstruction.
3.10.6.2 - Half-lifeA tracer can leave a region by biological clearance or stop being radioactive by nuclear decay. Distinguish these processes, combine their rates and calculate how activity changes inside a patient.
3.10.6.3 - Gamma CameraA gamma camera selects photon directions, converts gamma energy into light and amplifies the light into electrical pulses. Follow each conversion and see how the pattern of pulses estimates the position of an event.
3.10.6.4 - Use of High-Energy X-raysHigh-energy X-rays can deliver a useful dose to a deep tumour, but healthy tissue also absorbs energy. Learn how planning, beam shaping and changing beam directions improve the distribution of that dose.
3.10.6.5 - Use of Radioactive ImplantsA beta-emitting source placed in or beside a small tumour can concentrate dose near the target. Relate source position, beta range and treatment duration, while keeping this AQA model distinct from the wider range of clinical implants.
3.10.6.6 - Imaging ComparisonsAn imaging method is useful when it answers the particular clinical question with suitable detail, practical demands and risk. Compare image resolution, convenience and safety without treating any one method as universally best.

3.11 - Engineering Physics (Option C) / 3.11.1 - Rotational Dynamics

3.11.1.1 - Concept of Moment of InertiaMoment of inertia measures how strongly an object resists angular acceleration about a chosen axis. Calculate it by weighting each mass by the square of its distance from that axis, then use the result to compare rotating designs.
3.11.1.2 - Rotational Kinetic EnergyA flywheel stores kinetic energy in its rotation. Follow the energy from moving mass elements to a complete wheel, calculate the energy available as it slows, and explain how flywheels support engines, vehicles and production machinery.
3.11.1.3 - Rotational MotionUse angular displacement, velocity and acceleration to describe rotation. Graphs reveal how the motion changes, while constant-acceleration equations connect speeds, times and angles, including stopping and reversal.
3.11.1.4 - Torque and Angular AccelerationTorque is the turning effect of a force about an axis. Identify its lever arm, combine opposing torques, then apply the rotational form of Newton’s second law to wheels, brakes and a falling-mass experiment.
3.11.1.5 - Angular MomentumAngular momentum changes only when a resultant external torque acts. Use that principle to explain sports movements, solve clutch problems and calculate the effect of a torque acting over time.
3.11.1.6 - Work and PowerTorque transfers energy as an object turns. Derive work and power equations, distinguish motor work from kinetic-energy gain, and use free deceleration to estimate the resisting torque in a real machine.

3.11 - Engineering Physics (Option C) / 3.11.2 - Thermodynamics and Engines

3.11.2.1 - First Law of ThermodynamicsTrack energy transferred by heating and by work, using the AQA sign convention to explain changes in a gas and energy transfers over a complete cycle.
3.11.2.2 - Non-Flow ProcessesUse the physical constraint on a fixed amount of ideal gas to choose a gas law, calculate its new state and account for heat and work.
3.11.2.3 - The p-V DiagramRead pressure–volume paths, convert graphical area into signed work, and use loop direction to interpret the energy balance of a gas cycle.
3.11.2.4 - Engine CyclesConnect the four physical strokes to ideal and measured pressure–volume cycles, then distinguish fuel input, cylinder work and useful shaft output.
3.11.2.5 - Second Law and EnginesUse the Second Law to set an engine’s best possible work efficiency, then distinguish unavoidable heat rejection from additional real losses and useful heat recovery.
3.11.2.6 - Reversed Heat EnginesFollow energy from cold to hot using work input, choose the correct coefficient of performance and compare real heat pumps with their reversible limit.

3.12 - Turning Points in Physics (Option D) / 3.12.1 - The Discovery of the Electron

3.12.1.1 - Cathode RaysA discharge tube turns an insulating gas into a conductor. Follow how collisions sustain a stream of electrons, and distinguish those electrons from the light that makes the discharge visible.
3.12.1.2 - Thermionic Emission of ElectronsHeating a cathode releases electrons; an electric field then accelerates them. Separating these two jobs explains both the construction of an electron gun and the relation between its accelerating voltage and beam speed.
3.12.1.3 - Specific Charge of the ElectronA beam’s response to a known magnetic field reveals its charge-to-mass ratio. The fine-beam method connects energy and circular motion, while comparisons across materials and with hydrogen ions explain why the result changed the model of the atom.
3.12.1.4 - Millikan's Oil-Drop ExperimentA falling oil drop reveals its mass through viscous drag. Balancing that same drop with an electric field then reveals its charge. Repeating the measurement tests whether charge varies continuously or comes in discrete units.

3.12 - Turning Points in Physics (Option D) / 3.12.2 - Wave-Particle Duality

3.12.2.1 - Newton and HuygensNewton and Huygens could both account for familiar reflection and refraction, yet their models made opposite predictions about light speed inside glass. Compare the physical reasoning and see why a successful prediction is a stronger test than the reputation of a scientist.
3.12.2.2 - Young's double-slit evidenceYoung’s experiment turned the debate about light into a question about a surprising observation: adding light from a second slit can produce darkness. Follow the superposition argument and distinguish persuasive evidence from immediate acceptance.
3.12.2.3 - Electromagnetic wavesMaxwell predicted waves from electric and magnetic theory. Fizeau’s light-speed measurement and Hertz’s radio-wave experiments let physicists test the prediction and connect light with electromagnetism.
3.12.2.4 - The discovery of photoelectricityBlack-body radiation challenged continuous energy exchange, and photoelectric observations challenged a purely classical wave account of light. Separate Planck’s quantised oscillators from Einstein’s light quanta, then use energy conservation to test the photon explanation.
3.12.2.5 - Wave–particle dualityElectrons carry charge and arrive in localised interactions, yet a beam can produce diffraction. Use de Broglie’s relation to connect that wave evidence to momentum and to predict how an accelerating voltage changes the pattern.
3.12.2.6 - Electron microscopesA short electron wavelength helps a TEM reveal fine internal structure, while an STM uses tunnelling to map a conducting surface. Calculate the wavelength scale first, then distinguish it from the practical requirements and limits of each instrument.

3.12 - Turning Points in Physics (Option D) / 3.12.3 - Special Relativity

3.12.3.1 - The Michelson-Morley ExperimentMichelson and Morley used interference to test whether motion through a proposed light-carrying ether changed light's round-trip travel time. The important evidence was the absence of the predicted change when the apparatus was rotated.
3.12.3.2 - Einstein's Theory of Special RelativitySpecial relativity describes measurements made in inertial frames. Its two postulates give all these frames the same physical laws and the same vacuum light speed, even when they disagree about an object's velocity.
3.12.3.3 - Time DilationA clock moving relative to an inertial laboratory records less elapsed time than the laboratory assigns to the same pair of tick events. Learn to identify those events, derive the relationship with a light clock and test its consequences using muon survival.
3.12.3.4 - Length ContractionA moving object's length depends on the frame in which its end positions are measured. Use simultaneous measurements in one frame, identify the object's rest length and keep journey distances and times in the same frame.
3.12.3.5 - Mass and EnergySeparate rest energy, total energy and kinetic energy before calculating at relativistic speeds. The AQA mass-versus-speed convention and Bertozzi's independent measurements show why increasing energy drives a massive particle towards, but never to, the vacuum speed of light.

3.13 - Electronics (Option E) / 3.13.1 - Sensing Devices

3.13.1.1 - MOSFETAn insulated gate lets a small sensor signal control a larger load current. Learn to interpret N-channel enhancement-mode MOSFET characteristics and calculate what happens in a switching circuit.
3.13.1.2 - Zener diodeA reverse-biased Zener can provide a known voltage if its current is kept within the right range. Use its characteristic and simple resistor calculations to distinguish a working reference from an unsafe or unreliable circuit.
3.13.1.3 - PhotodiodeLight produces a current in a photodiode. Learn to read its electrical and spectral characteristics, trace the output of a reverse-biased detector and follow the signal from optical pulses or a scintillator.
3.13.1.4 - Hall effect sensorA Hall sensor turns a magnetic-field change into an electrical signal. Use calibration to monitor orientation and use pulse counting to measure rotational speed without contact.

3.13 - Electronics (Option E) / 3.13.4 - Op-Amp Circuits

3.13.4.1 - Inverting AmplifiersNegative feedback lets an op-amp produce a predictable inverted output. Follow the current through the input and feedback resistors to derive the gain, then check when the required output is physically possible.
3.13.4.2 - Non-Inverting AmplifiersApply the non-inverting gain equation without losing its added 1. Identify the feedback junction, choose resistors and output limits, and explain why a voltage follower can preserve a sensor signal even though its voltage gain is one.
3.13.4.3 - Summing and Difference AmplifiersA summing amplifier forms a weighted inverted total, while a difference amplifier responds to the separation between two voltages. Use the correct signed relationship, understand the resistor matching, and distinguish independent input contributions from cancellation of shared interference.
3.13.4.4 - Real Operational AmplifiersReal op-amps have finite gain, loading effects and a limited frequency response. Read logarithmic response curves, calculate the gain–bandwidth trade-off, and use output-range and bandwidth requirements together when judging a design.

3.13 - Electronics (Option E) / 3.13.6 - Communication Systems

3.13.6.1 - Principles of Communication SystemsA real-time communication system delivers information as it is produced, with a short delay. Follow a signal from its source, through a transmission medium, to an output, and explain why each stage is needed.
3.13.6.2 - Transmission MediaChoose a transmission medium by explaining how it carries information and weighing capacity, range, installation cost and interception risk. Radio propagation and satellite relay make communication possible where a direct cable or line of sight is unavailable.
3.13.6.3 - Time-Division MultiplexingTime-division multiplexing lets several information streams share one link by taking turns. Follow the slots through a frame, explain how timing preserves their identities, and calculate how the finite capacity is shared.
3.13.6.4 - AM and FMModulation varies a carrier so that it conveys information. Compare the waveforms and bandwidth of AM and FM, read their frequencies from time graphs, and decide whether a channel can carry the signal.