Key term
OCR A-Level Physics B H557
Planning
Implementing
Analysis
Evaluation
Practical Skills
Use of Apparatus and Techniques
Fundamental Data Analysis
Imaging and Signalling
Topic overviewReal images and the curvature of wave-frontsLens power and focal lengthThe thin lens equation and the Cartesian conventionLinear magnificationMeasuring the power and focal length of a converging lensImages as arrays of numbersBits, bytes and the information in an imageEnhancing a digital imageWave-forms, frequency and wave speedSampling and digitising an analogue signalNoise, resolution and digital transmissionPolarisation of electromagnetic waves
Sensing
Topic overviewCurrent and the flow of chargePotential difference, e.m.f. and energy transferResistance, conductance and Ohm's lawSeries and parallel combinationsPower and energy in electric circuitsInternal resistance and e.m.f.Kirchhoff's laws and conservation in circuitsResistivity and conductivityCharge carrier number density in metals, semiconductors and insulatorsCurrent-potential difference characteristics and circuit componentsThe potential dividerSensing circuits and calibration
Mechanical Properties of Materials
Topic overviewElastic and plastic deformation and fractureHooke's law and force-extension graphsElastic strain energyStress, strain and the Young modulusMeasuring the Young modulus and fracture stress of a metalDescribing and comparing materialsMetals, ceramics and polymersDirect evidence for the size and spacing of particles
Waves and Quantum Behaviour
Topic overviewWaves, phase and superpositionStanding waves on stringsStanding waves in air columns and the speed of soundRefraction, refractive index and Snell's lawTwo-slit interferenceDiffraction at a narrow apertureThe diffraction gratingMeasuring the wavelength of lightPhotons and the quantum E = hfEvidence that photons exchange energy in quantaQuantum behaviour: phasors and probability of arrivalElectron diffraction and the de Broglie wavelength
Space, Time and Motion
Topic overviewScalars, vectors and their representationResolving and adding vectorsDescribing motion: displacement, velocity and accelerationMotion graphsThe kinematic equations for constant accelerationProjectiles and motion in two dimensionsMeasuring motion in the laboratoryDetermining the acceleration of free fallNewton's laws of motionTerminal velocity and resistive forcesMomentum and impulseConservation of momentum and collisionsWork, energy and its conservationPower and modelling motion in small time steps
Creating Models
Topic overviewCapacitance and charge storageEnergy stored on a capacitorCapacitor discharge and the exponential modelThe time constant of an RC circuitCharging a capacitorInvestigating capacitor charge and dischargeRadioactive decay as a random processActivity, decay constant and half-lifeDetermining the half-life of an isotopeIterative numerical models of exponential changeExponential curves on linear and logarithmic scalesSimple harmonic motion: the defining relationshipSolutions and graphs of simple harmonic motionModelling oscillations step by stepEnergy in simple harmonic motionPeriod of a mass–spring system and a simple pendulumFree and forced vibrations, damping and resonance
Out Into Space
Topic overviewGravitational and kinetic energy changesMotion in a uniform gravitational fieldGravitational force and the radial fieldGravitational field strengthGravitational potential energy in a radial fieldGravitational potential and equipotentialsGraphs and diagrams of gravitational fieldsAngular velocity and motion in a horizontal circleCircular gravitational orbits
Our Place in the Universe
Matter: Very Simple
Topic overviewEnergy transfer and specific thermal capacityFinding specific thermal capacity by an electrical methodIdeal gases and the gas lawsInvestigating the gas laws and absolute zeroMoles, the Avogadro constant and the Boltzmann constantThe equation of state for an ideal gasImpulse and force–time graphsThe kinetic theory of ideal gasesTemperature, average energy per particle and internal energyRandom walk of molecules in a gas
Matter: Hot or Cold
Electromagnetism
Topic overviewMagnetic flux, B-fields and flux linkageElectromagnetic induction: Faraday's and Lenz's lawsGraphs of current, flux and induced e.m.f.The dynamoThe transformerEddy currents and real transformersForces on current-carrying conductorsMagnetic circuits, permeance and machine designInvestigating induction, flux density and transformers
Charge and Field
Topic overviewThe uniform electric fieldRadial fields and the inverse square lawElectric potential and potential energyField and potential graphsField lines and equipotential surfacesThe electronvolt and accelerating chargesMillikan's experiment and the discreteness of chargeMoving charges in magnetic fieldsComparing electric and gravitational fields
Probing Deep Into Matter
Topic overviewParticle accelerators and high-energy beamsScattering and the nuclear atomPaths of scattered particles and closest approachDiscrete energy levels in atomsElectron standing waves and the confined electronQuarks, hadrons and leptonsConservation laws and nuclear equationsCharged particles in detectors and magnetic fieldsRelativistic energy and the relativistic factor
Ionising Radiation and Risk
Topic overviewThe nature of ionising radiationsEffects on living tissue and radiation safetyAbsorbed dose, effective dose and riskBinding energy and nuclear stabilityThe Nuclear Valley and modes of decayFission, fusion and nuclear powerActivity, half-life and the decay constantInvestigating absorption and half-life
Our Place in the Universe
- 5 subtopics
- 13 things to know
- Components 01, 02 and 03
What Our Place in the Universe covers
Our Place in the Universe is examined in all three written papers — the specification states that Components 01, 02 and 03 each assess content from across all the teaching modules, so nothing is confined to one paper. It covers radar measurement of distance and velocity, distance measured in units of time, relativistic time dilation, evidence for the hot big bang and logarithmic scales of magnitude.
Where it is assessed
Components 01, 02 and 03
Every module can be assessed on any of the three papers.
Check the OCR specification ↗The 5 subtopics
Each one has its own page.
- Radar measurement of distance and velocityRecall questions on timing an echo and why the time is halved, distances to the Moon and planets, relative velocity from successive pulses, pulse length and timing uncertainty, and the method's limits.Open →
- Distance measured in units of timeRecall questions on the invariance behind it, light-years and light-seconds in metres, the modern definition of the metre, seeing objects as they were, and the limit on what can be observed.Open →
- Relativistic time dilationRecall questions on γ = 1/√(1 − v²/c²) and its values at rest, 0.60c and 0.80c, time dilation and dilated intervals, why it goes unnoticed, muon lifetimes as evidence, γ growing without limit near c, the speed at which γ is 2.0, why massive objects cannot reach c, satellite navigation, and the symmetry between observers.Open →
- Evidence for the hot big bangRecall questions on cosmological red-shift, Hubble's law and the Hubble constant with its units, z = Δλ/λ = v/c, recession speed and distance calculations, why the Earth is not at the centre, estimating the age of the universe from 1/H₀ and its limits, the cosmic microwave background and its 2.7 K temperature, and the abundance of helium.Open →
- Logarithmic scales of magnitudeRecall questions on logarithmic scales and why astronomy uses them, orders of magnitude, the sizes of atoms, nuclei and the Earth, the distances to the nearest star and the edge of the observable universe, the masses of the Sun and a proton, placing values on a logarithmic scale, brightness decades, reading ratios, and why the scale has no zero.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
Radar ranges an asteroid at 6.000×10⁹ m then 5.999×10⁹ m, 100 s later. Find its velocity, justify assuming constant c, and explain echo uncertainty.
Key term
Why do we see distant objects as they once were, how is the metre defined, and why quote astronomical distances as times?
Key term
Describe how a radar pulse measures the distance to a planet, and state and justify the equation used.
Key term
State Hubble's law.
Evaluation
What advantage does a logarithmic scale give when comparing quantities of very different size?
Key term
What does it mean to measure a distance in units of time?
Key term
What is the expression for the relativistic factor γ?
Key term
How is red-shift related to recession speed for small red-shifts?
Key term
How is a radar pulse used to measure the distance to a planet?
Key term
Why is it possible to define distance in units of time?
Key term
How is a time interval measured in the laboratory related to the interval measured in the moving frame?
Key term
A galaxy shows a red-shift of 0.020. What is its recession speed?
Take Our Place in the Universe further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Light-year vs Year
Light-year: a distance rather than an interval: how far a beam of radiation travels through a vacuum in 3.16 × 10⁷ s, about 9.5 × 10¹⁵ m. Year: An interval of time, about 3.16 × 10⁷ s, taken by the Earth to travel once around the Sun.
Red-shift z vs Recession speed v
Red-shift z: the fraction by which the wavelength has been stretched, Δλ/λ, a pure number carrying no units. Recession speed v: How fast a galaxy is moving away from us, in m s⁻¹, obtained by multiplying the fractional change in wavelength by c whenever that change is small.
d = ct vs d = ct/2
d = ct: the distance covered on a one-way trip, the travel time multiplied by the speed of the wave. d = ct/2: The distance to a reflector, where the echo time covers the journey there and back and so must be halved before multiplying by the speed of the wave.
Questions from this topic
Each one with the model answer underneath.
- 1
How is a radar pulse used to measure the distance to a planet?
Model answer
A short pulse is transmitted, the time until its echo returns is measured, and the distance is half that time multiplied by the speed of light.
- 2
What equation gives distance from a radar echo time?
Model answer
The distance is d = ct/2, where t is the round-trip time of the pulse.
- 3
Why is the echo time halved in a radar distance calculation?
Model answer
The pulse travels to the object and back again, so it covers twice the distance being measured.
- 4
A radar echo from Venus returns after 300 s. How far away is Venus?
Model answer
d = ct/2 = 3.00 × 10⁸ × 150 = 4.5 × 10¹⁰ m.
- 5
A radar echo from the Moon returns after 2.56 s. What is the Earth–Moon distance?
Model answer
d = ct/2 = 3.00 × 10⁸ × 1.28 = 3.84 × 10⁸ m.
- 6
Why is radar unsuitable for measuring distances to other stars?
Model answer
The reflected pulse would be far too weak to detect after spreading over such distances, and the round trip would take years.
What is inside Levo
Six ways to work the same material.
Our Place in the Universe revision questions
- What does Our Place in the Universe cover in OCR A-Level Physics B?
- 5 subtopics: radar measurement of distance and velocity, distance measured in units of time, relativistic time dilation, evidence for the hot big bang and logarithmic scales of magnitude. Each one has its own page with questions and model answers.
- How is Our Place in the Universe organised?
- By the OCR H557 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Our Place in the Universe, 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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