Numbers
AQA A-Level Physics 7408
Measurements and Their Errors
Particles and Radiation
Topic overviewConstituents of the atomStable and unstable nucleiParticles, antiparticles and photonsParticle interactionsClassification of particlesQuarks and antiquarksApplications of conservation lawsThe photoelectric effectCollisions of electrons with atomsEnergy levels and photon emissionWave-particle duality
Waves
Mechanics and Materials
Electricity
Further Mechanics and Thermal Physics
Fields and Their Consequences
Topic overviewFieldsNewton's lawGravitational field strengthGravitational potentialOrbits of planets and satellitesCoulomb's lawElectric field strengthElectric potentialCapacitanceParallel plate capacitorEnergy stored by a capacitorCapacitor charge and dischargeMagnetic flux densityMoving charges in a magnetic fieldMagnetic flux and flux linkageElectromagnetic inductionAlternating currentsTransformers
Nuclear Physics
AstrophysicsOptional topic
Topic overviewAstronomical telescope consisting of two converging lensesReflecting telescopesSingle dish radio telescopes, I-R, U-V and X-ray telescopesAdvantages of large diameter telescopesClassification by luminosityAbsolute magnitude, MClassification by temperature, black-body radiationPrinciples of the use of stellar spectral classesThe Hertzsprung-Russell (HR) diagramSupernovae, neutron stars and black holesDoppler effectHubble's lawQuasarsDetection of exoplanets
Medical PhysicsOptional topic
Topic overviewPhysics of visionDefects of vision and their correction using lensesEar as a sound detection systemSensitivity and frequency responseDefects of hearingSimple ECG machines and the normal ECG waveformUltrasound imagingFibre optics and endoscopyMagnetic resonance (MR) scannerThe physics of diagnostic X-raysImage detection and enhancementAbsorption of X-raysCT scannerImaging techniquesHalf-lifeGamma cameraUse of high-energy X-raysUse of radioactive implantsImaging comparisons
Engineering PhysicsOptional topic
Turning Points in PhysicsOptional topic
Topic overviewCathode raysThermionic emission of electronsSpecific charge of the electronPrinciple of Millikan's determination of the electronic charge, eNewton's corpuscular theory of lightSignificance of Young's double slits experimentElectromagnetic wavesThe discovery of photoelectricityWave–particle dualityElectron microscopesThe Michelson-Morley experimentEinstein's theory of special relativityTime dilationLength contractionRelativistic mass and energy
ElectronicsOptional topic
Topic overviewMOSFET (metal-oxide semiconducting field-effect transistor)Zener diodePhotodiodeHall effect sensorDifference between analogue and digital signalsLC resonance filtersThe ideal operational amplifierInverting amplifier configurationNon-inverting amplifier configurationSumming amplifier configurationReal operational amplifiersCombinational logicSequential logicAstablesPrinciples of communication systemsTransmission mediaTime-division multiplexingAmplitude (AM) and frequency modulation (FM) techniques
Fields and Their Consequences
- 18 subtopics
- 76 things to know
- Papers 2 and 3
What Fields and Their Consequences covers
Fields and their consequences is examined on Papers 2 and 3, and is the largest topic in the second year. It treats gravitational, electric and magnetic fields side by side, drawing out what they share, then covers capacitance and electromagnetic induction.
Where it is assessed
Papers 2 and 3
Core content, then practical skills and data analysis.
Check the AQA specification ↗The 18 subtopics
Each one has its own page.
- FieldsWhat a force field is, and the parallels between gravitational and electrostatic fields.Open →
- Newton's lawNewton's law of gravitation, the gravitational constant, and the inverse-square relationship.Open →
- Gravitational field strengthDefining g by force per unit mass, radial fields, and reading field lines.Open →
- Gravitational potentialPotential and potential difference, equipotential surfaces, and the graphs of g and V against r.Open →
- Orbits of planets and satellitesOrbital speed and period, T² ∝ r³, the energy of an orbiting satellite, escape velocity and synchronous orbits.Open →
- Coulomb's lawThe force between point charges, permittivity of free space, and comparison with gravitation.Open →
- Electric field strengthField strength in uniform and radial fields, E = V/d, and the path of a charge in a uniform field.Open →
- Electric potentialAbsolute potential and potential difference, equipotentials, and the relationship between E and V.Open →
- CapacitanceDefining capacitance, the farad, and the relationship between charge, voltage and capacitance.Open →
- Parallel plate capacitorPermittivity and relative permittivity, dielectrics, and how a polar molecule responds to a field.Open →
- Energy stored by a capacitorThe three energy formulae, and finding the energy from the area under a charge-voltage graph.Open →
- Capacitor charge and dischargeThe time constant, the exponential equations, and the log-linear graphs used to find RC.Open →
- Magnetic flux densityThe force on a current-carrying wire, Fleming's left hand rule, and the current balance experiment.Open →
- Moving charges in a magnetic fieldF = BQv, circular motion in a field, and the cyclotron.Open →
- Magnetic flux and flux linkageMagnetic flux and flux linkage, and how both vary for a rotating coil.Open →
- Electromagnetic inductionFaraday's law and Lenz's law, the emf induced by a moving conductor, and the alternator.Open →
- Alternating currentsPeak, peak-to-peak and root mean square values, and using an oscilloscope.Open →
- TransformersThe transformer equation, efficiency, and why the National Grid transmits at high voltage.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Process
What is potential, and how does gravitational interaction differ from electrostatic?
Key term
What type of interaction gives rise to gravitational force fields?
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What is Newton's law of gravitation, and between which objects does gravity act?
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What do the symbols in F = Gm₁m₂/r² stand for, and what units does G take?
Process
If the distance between two point masses is halved, what happens to the gravitational force between them?
Process
What is gravitational field strength, and what does the spacing of field lines show?
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How is gravitational field strength defined by force and mass, and what unit does it take?
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What does g = GM/r² show, and in what direction does the field point?
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What happens to g when the distance doubles, and from where is r measured?
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How is work done in a gravitational field calculated, and what is potential difference?
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What is gravitational potential at distance r, and what are equipotential surfaces?
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What do the graphs of field strength and of potential against distance look like?
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How is gravitational field strength related to the gradient of gravitational potential?
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How are orbital speed and orbital period calculated for a satellite?
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Why does T² ∝ r³ hold, and what is the kinetic energy of an orbiting satellite?
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What is the potential energy of an orbiting satellite, and why is it negative?
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What is the total energy of an orbiting satellite, and what does a negative value mean?
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How do the kinetic and potential energies of a satellite compare, and what is escape velocity?
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How is escape velocity calculated, and what is a synchronous orbit?
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What is obtained by taking logarithms of T² = kr³, and what gradient results?
Process
What units does permittivity of free space take, and how strong is the electrostatic force between particles?
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How does the sign of the charges determine whether the force attracts or repels?
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What is the value and unit of 1/4πε₀, and what information is needed for an estimate?
Key term
How is electric field strength defined, and what do field lines represent?
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What units does electric field strength take, and how is E = V/d derived?
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How does E = V/d follow from E = F/Q, and what path does a charge take in a uniform field?
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What happens to E when the distance from a point charge doubles, and how are field patterns investigated?
Key term
How is absolute electric potential defined, and where is its zero?
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How is work done on a charge calculated, and why is none done along an equipotential?
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What is the potential at distance r from a point charge, and what does ε₀ represent?
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How does field strength relate to potential gradient, and why is there a minus sign?
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How is capacitance defined, and what does it tell you about a capacitor?
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What do the symbols in C = Q/V mean, what is the unit of capacitance, and how is the farad expressed in coulombs and volts?
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Which rearrangements find capacitance and potential difference, and what happens to the potential difference if capacitance increases at constant charge?
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What do εᵣ and A represent in the parallel plate capacitor formula?
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What does d stand for in the capacitance formula, and what is a dielectric?
Process
How does a polar molecule respond to an applied field, and how is relative permittivity measured?
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What instrument can be used to investigate how capacitance varies with plate area and plate separation?
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How is the energy stored by a capacitor calculated, and how is it read from a graph?
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What does E = ½Q²/C mean, and how is E = ½CV² derived from E = ½QV?
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What does the gradient of a charge against potential difference graph give, and what shape is it?
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What does the gradient of a Q-t graph give, and how does current vary during discharge?
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How is the time constant defined, and why is it measured in seconds?
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How can the time constant be found graphically from a discharge curve?
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How do charge and potential difference vary with time during discharge?
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What do I₀ and RC represent in the discharge current equation?
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What happens to discharge current over time, and why does charging include (1 − e^(−t/RC))?
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What shape is a log-linear discharge plot, and how does its gradient give the time constant?
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How is the force on a current-carrying wire calculated, and when does F = BIl apply directly?
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How is magnetic flux density defined, and what does the first finger show in Fleming's left hand rule?
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How is a balance reading converted into a force when measuring the force on a current-carrying wire?
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What apparatus is used to measure the magnetic force on a wire in the required practical investigating F = BIl?
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What do the symbols in F = BQv mean, and what units do they take?
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When does F = BQv apply, and how is Fleming's left-hand rule used for a positive charge?
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Why does a charged particle follow a circular path in a uniform magnetic field?
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How is the radius of the circular path found, and what provides the centripetal force?
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What is cyclotron frequency, and why is it independent of the particle's speed?
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What orientation does Φ = BA assume, and what happens when the field is at an angle?
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What units do magnetic flux and flux linkage take, and what is the formula for a rotating coil?
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What does N stand for, and what is the flux linkage when the coil face is perpendicular or parallel?
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Which quantities give magnetic flux, and how does orientation enter the formula?
Key term
What unit does magnetic flux take, and how do flux and flux linkage differ?
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What apparatus investigates how flux linkage varies, what does the oscilloscope show, and why is an oscilloscope used rather than a voltmeter?
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How is induced emf calculated, and what does Lenz's law state?
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What is flux linkage, and what emf does a straight conductor induce?
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What condition does ε = BLv assume, and how does emf vary for a rotating coil?
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What does ω represent, and at what orientation is the peak emf reached?
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What is a root mean square current, and how does it relate to the peak value?
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How is peak voltage found from rms voltage, and what is peak-to-peak value?
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How does an oscilloscope measure time, and what do its axes show?
Key term
What type of display does an oscilloscope produce for an ac signal?
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When mains voltage is quoted as 230 V, is this the peak value or the rms value?
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What is the transformer equation, and why must a transformer use alternating current?
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Why is power sent at high voltage across the National Grid?
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Why is the voltage stepped down before electricity reaches homes?
Take Fields and Their Consequences further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Gravitational field strength vs Gravitational potential
Gravitational field strength: force per unit mass. Gravitational potential: work per unit mass from infinity.
Electric field strength vs Electric potential
Electric field strength: force per unit positive charge. Electric potential: work per unit positive charge from infinity.
Magnetic flux vs Magnetic flux linkage
Magnetic flux: field passing through an area. Magnetic flux linkage: flux multiplied by linked turns.
Questions from this topic
Each one with the model answer underneath.
- 1
What is a force field?
Model answer
A region where a body feels a force without being touched.
- 2
How can a force field be represented mathematically?
Model answer
As a vector quantity, having both magnitude and direction.
- 3
How is the direction of a force field vector established?
Model answer
By inspection of the physical situation.
- 4
What type of interaction gives rise to gravitational force fields?
Model answer
The interaction of mass.
- 5
What type of interaction produces electrostatic force fields?
Model answer
The interaction of static charge.
- 6
What gives rise to magnetic force fields?
Model answer
The interaction between moving charges.
What is inside Levo
Six ways to work the same material.
Fields and Their Consequences revision questions
- What does Fields and Their Consequences cover in AQA A-Level Physics?
- 18 subtopics: fields, newton's law, gravitational field strength, gravitational potential, orbits of planets and satellites, coulomb's law, electric field strength, electric potential, capacitance, parallel plate capacitor, energy stored by a capacitor, capacitor charge and discharge, magnetic flux density, moving charges in a magnetic field, magnetic flux and flux linkage, electromagnetic induction, alternating currents and transformers. Each one has its own page with questions and model answers.
- How is Fields and Their Consequences organised?
- By the AQA 7408 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Fields and Their Consequences, 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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