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
Medical Physics
The physics of diagnostic X-rays
- 6 things to know
- Paper 3, section B
Overview
X-ray production, the continuous and characteristic spectra, and controlling intensity and energy.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Numbers
Why does the minimum wavelength carry the highest energy, and what makes up the spectrum?
Process
How are characteristic X-rays produced, and what sets their photon energy?
Process
Why is a rotating anode used, and what controls beam intensity?
Key term
What is the purpose of placing an aluminium filter in the X-ray beam?
Process
If the tube current is increased, what happens to the maximum photon energy of the X-ray beam?
Questions from this subtopic
Each one with the model answer underneath.
- 1
In an X-ray tube, how are free electrons initially produced at the cathode?
Model answer
Electrons are emitted from a heated cathode by thermionic emission.
- 2
Once emitted from the cathode, how are electrons made to travel towards the anode in an X-ray tube?
Model answer
Electrons are accelerated across a high potential difference towards the anode.
- 3
What happens to the electrons when they reach the metal target in an X-ray tube?
Model answer
Electrons strike the metal target and lose kinetic energy.
- 4
In what form is the lost kinetic energy of electrons released when they strike the target?
Model answer
The energy is released as X-ray photons.
- 5
State the formula for the maximum photon energy of X-rays produced in an X-ray tube.
Model answer
Eₘₐₓ = eV, where e is the elementary charge and V is the accelerating potential difference.
- 6
What determines the maximum energy of X-ray photons produced in an X-ray tube?
Model answer
The kinetic energy of the incident electrons, which is determined by the accelerating potential difference.
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