Key term
Eduqas A-Level Physics A420QS
Basic Physics
Kinematics
Dynamics
Energy Concepts
Circular Motion
Vibrations
Topic overviewDefining simple harmonic motionFrequency, period, amplitude and phaseThe displacement equation for simple harmonic motionVelocity in simple harmonic motionDisplacement and velocity graphsThe mass-spring oscillatorThe simple pendulumEnergy in simple harmonic motionFree oscillation and dampingForced oscillation and resonance
Kinetic Theory
Thermal Physics
Conduction of Electricity
Resistance
Topic overviewPotential difference and the voltResistance, Ohm's law and the ohmI–V characteristics of a metal wire and a filament lampElectrical power and energy transferThe microscopic origin of resistanceResistivity and the equation R = ρl/AResistance and temperatureSuperconductivity and the transition temperatureHigh temperature superconductors and their uses
D.C. Circuits
Capacitance
Solids Under Stress
Electrostatic and Gravitational Fields of Force
Topic overviewElectric field strength and Coulomb's lawGravitational field strength and Newton's law of gravitationField lines and equipotential surfacesElectric potential and potential energyGravitational potential and potential energyResultant fields and potentials from several sourcesComparing electric and gravitational fields
Using Radiation to Investigate Stars
Orbits and the Wider Universe
Topic overviewKepler's laws of planetary motionNewton's law of gravitation applied to planets and satellitesDeriving Kepler's third law for a circular orbitUsing orbital data to find the mass of the central objectGalactic rotation curves and dark matterThe centre of mass of a two-body systemThe Doppler shift of spectral lines and radial velocityMasses in a double system from radial velocity dataHubble's law, the age of the universe and its fate
The Nature of Waves
Wave Properties
Topic overviewDiffraction at slits and obstaclesWavelength, slit width and the spread of the beamThe principle of superpositionCoherence and the conditions for interferencePath difference and the interference conditionsYoung's double slit experimentThe historical importance of Young's experimentThe diffraction gratingComparing the grating with the double slitStationary waves
Refraction of Light
Photons
Topic overviewPhotons and the quantum of lightDemonstrating the photoelectric effectThe vacuum photocell and stopping potentialEinstein's equation and the energy graphThe electromagnetic spectrum and photon energiesLine emission and line absorption spectraAtomic energy levelsIonisation energy from an energy level diagramElectron diffraction and the de Broglie relationship
Lasers
Nuclear Decay
Topic overviewSpontaneous decay and the nature of α, β and γ radiationNuclear transformation equations and nuclide notationDistinguishing α, β and γ by ionisation, penetration and rangeBackground radiation and gamma intensity with distanceActivity, the becquerel and the decay constantThe exponential decay law and half-life
Particles and Nuclear Structure
Topic overviewThe Rutherford alpha particle scattering experimentCoulomb repulsion in the plum pudding and Rutherford modelsQuarks and leptons: the first generationAntiparticles, annihilation and their symbolsHadrons: baryons, antibaryons and mesonsQuark composition of the proton, neutron and pionsThe four fundamental interactionsConservation laws in particle reactions
Nuclear Energy
Magnetic Fields
Topic overviewThe motor effect and Fleming's left-hand ruleF = BIl sinθ and measuring magnetic flux densityThe force on a moving charge, F = Bqv sinθThe Hall effect and the Hall probeMagnetic fields due to a straight wire and a solenoidForces between current-carrying conductorsCharged particle beams and accelerators
Electromagnetic Induction
Option A: Alternating CurrentsOption A
Topic overviewElectromagnetic induction in a rotating coilFrequency, period, peak and rms valuesMean power dissipated in a resistorUsing an oscilloscope to measure voltage and frequencyInductors in a.c. circuits and inductive reactanceCapacitors in a.c. circuits and capacitive reactancePhasors, phase angle and impedanceResonance in the series RCL circuit and the Q factor
Option B: Medical PhysicsOption B
Topic overviewThe nature and properties of X-raysX-ray production and controlling the beamAttenuation of X-rays and half-value thicknessX-ray imaging, fluoroscopy and radiographyComputed tomography scanningUltrasound generation and acoustic impedanceUltrasound scanning and the Doppler techniqueMagnetic resonance and MRIRadiation effects on living matter and dosimetryRadionuclide tracers, the gamma camera and PET
Option C: The Physics of SportsOption C
Topic overviewCentre of gravity, stability and topplingMoments in muscle systems and other sporting contextsImpulse and Newton's second law in sportThe coefficient of restitutionMoment of inertiaAngular acceleration, torque and angular momentumConservation of angular momentum and rotational energyProjectiles, Bernoulli's equation and drag
Option D: Energy and the EnvironmentOption D
Mathematical Requirements (Appendix C)
Topic overviewUnits, prefixes and standard formSignificant figures and arithmetic meansUncertainty and how uncertainties combineRatios, proportionality and order of magnitude estimatesRearranging and solving physics equationsLogarithms, exponentials and decayResolving vectors, Pythagoras and trigonometryRadians, small angles, areas and volumesStraight-line graphs, gradients and interceptsTangents, areas under curves and logarithmic plots
Refraction of Light
- 6 subtopics
- 18 things to know
- Component 3
What Refraction of Light covers
Refraction of Light is examined in Component 3, Light, Nuclei and Options, Section A, which every student sits. It covers refractive index and the speed of light, Snell's law, Snell's law and the wave model, total internal reflection and the critical angle, multimode optical fibres and multimode dispersion and monomode fibres.
Where it is assessed
Component 3
Light, Nuclei and Options, Section A, the compulsory core.
Check the Eduqas specification ↗The 6 subtopics
Each one has its own page.
- Refractive index and the speed of lightRefractive index of a medium and refractive index of a vacuum.Open →
- Snell's lawRecall questions on Snell's law in its two-medium and air forms, why angles are measured from the normal, which way a ray bends entering a denser or a less dense medium, worked calculations at named boundaries, and what is plotted and what the gradient gives.Open →
- Snell's law and the wave modelRecall questions on the wavefront explanation of refraction, why the wavefronts crowd together and pivot, how the geometry gives the ratio of the sines as the ratio of the speeds, what the particle model predicted instead, and which measurement settled the question.Open →
- Total internal reflection and the critical angleTwo conditions required for total internal reflection and critical angle.Open →
- Multimode optical fibresStructure of a step index optical fibre, multimode fibre and purpose of the outer protective coating on a fibre.Open →
- Multimode dispersion and monomode fibresMultimode dispersion and monomode fibre.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
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What is plotted to verify Snell's law, what does the gradient give, and why must the line pass through the origin?
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Explain refraction using the wave model of light.
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State the two conditions required for total internal reflection.
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What keeps the light inside the core of an optical fibre?
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What effect does multimode dispersion have on a pulse of light?
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Why is the refractive index of any material medium greater than one?
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Give the Snell's law relationship in terms of the two speeds
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Why do the wavefronts become closer together in the denser medium?
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Define the critical angle.
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What is meant by a multimode fibre?
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What is a monomode fibre?
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State the refractive index of a vacuum, and give the value usually used for air.
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Why are the angles in Snell's law measured from the normal and not from the surface?
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Why does the direction of the rays change when the wavefronts turn?
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Give the critical angle equation for a boundary with air.
Numbers
Calculate the critical angle at a core–cladding boundary where the core has a refractive index of 1.50 and the cladding 1.48.
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How does a monomode fibre overcome multimode dispersion?
Take Refraction of Light further
The same content, four other ways.
Questions from this topic
Each one with the model answer underneath.
- 1
Define the refractive index of a medium.
Model answer
The refractive index of a medium is the speed of light in a vacuum divided by the speed of light in that medium.
- 2
Give the equation defining refractive index and define each symbol.
Model answer
n = c/v, where n is the refractive index, c the speed of light in a vacuum in m s⁻¹ and v the speed of light in the medium in m s⁻¹.
- 3
Why has refractive index no unit?
Model answer
It is the ratio of two speeds, so the units cancel.
- 4
Why is the refractive index of any material medium greater than one?
Model answer
Light travels more slowly in a material than in a vacuum, so the ratio of the two speeds exceeds one.
- 5
State the refractive index of a vacuum, and give the value usually used for air.
Model answer
A vacuum has a refractive index of exactly one, and air is taken as one to three significant figures.
- 6
Calculate the speed of light in glass of refractive index 1.50, taking c as 3.00 × 10⁸ m s⁻¹.
Model answer
v = c/n = 3.00 × 10⁸ ÷ 1.50, which is 2.00 × 10⁸ m s⁻¹.
What is inside Levo
Six ways to work the same material.
Refraction of Light revision questions
- What does Refraction of Light cover in Eduqas A-Level Physics?
- 6 subtopics: refractive index and the speed of light, snell's law, snell's law and the wave model, total internal reflection and the critical angle, multimode optical fibres and multimode dispersion and monomode fibres. Each one has its own page with questions and model answers.
- How is Refraction of Light organised?
- By the Eduqas A420QS specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Refraction of Light, 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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