Key term
OCR GCSE Physics A J249
Electricity
Topic overviewCharge, and producing static electricityTransfer of electrons, and electric fieldsCurrent as a rate of flow of chargeCharge, current and timeSeries and parallel circuits, and circuit symbolsCurrent, potential difference and resistanceResistors whose resistance changes, and investigating themLinear and non-linear circuit elements from graphsNet resistance in series and parallelCircuits for measurement, and electrical power
Energy
Topic overviewConservation of energy, and energy storesEnergy changes on heating, and calculating themEnergy of a moving body, a spring and a raised objectDissipation, and energy transfer in domestic devicesPower ratings, and calculating efficiencyReducing unwanted energy transfer, and the rate of cooling
Forces
Topic overviewMeasuring distance and time, and calculating speedConverting units, and ratesVectors and scalars in motionDistance-time and velocity-time graphsAverage speed, and the equations of uniform motionHow objects interact, and forces as vectorsNewton's first lawNewton's second lawForce and the time taken to change velocityWork done, and stored energyPower, and Newton's third lawStretching, bending and compressing; elastic and plasticForce and extension, linear and non-linearThe spring constant, and work done in stretchingGravitational fields, weight and free fallCalculations with weight and gravitational field strengthTurning forces and the moment of a forceLevers and gearsPressure in fluids, and the force on a surface
Global Challenges
Topic overviewTypical speeds and everyday accelerationsReaction time, stopping distance and the dangers of large decelerationsEstimating stopping distances and the forces in a collisionEnergy resources, and trends in their useThe national grid, and step-up and step-down transformersWhy the national grid is efficient, and power in a transformerMains electricity: a.c., d.c. and the domestic supplyLive, neutral and earth wires, and electrical dangerRed-shift and the Big BangThe formation of the Sun, and radiation from bodiesThe solar system
Magnetism and Magnetic Fields
Matter
Topic overviewHow the atomic model changed, and the structure of the atomThe size of atoms, and defining densityDensity of the states of matter, and density calculationsConservation of mass in changes of stateHeating a system, and specific heat capacityCalculations with specific heat capacity and latent heatGas molecules, temperature and pressureCompressing a gas, and changing its volumeAtmospheric pressure and why it varies with height
Radioactivity
Topic overviewProtons, neutrons and isotopesUnstable nuclei and the emissions they give outBalancing nuclear equationsElectron energy levels, and radiation from atomsHalf-life and the randomness of decayPenetration of alpha, beta and gammaContamination and irradiation, and half-life as a hazardUses of nuclear radiationNuclear fission and fusion
Waves in Matter
Topic overviewAmplitude, wavelength, frequency and periodThe wave equationTransverse and longitudinal wavesSound crossing a boundary; reflection, transmission and absorptionModelling waves with ripples and soundElectromagnetic waves as transverse, and energy transferFrequency and wavelength across the spectrumWhat our eyes detect, and light as an electromagnetic waveUses of electromagnetic wavesHazards of ultraviolet, X-rays and gamma raysRay diagrams for reflection and refractionHow colour arises
Waves in Matter
- 12 subtopics
- 34 things to know
- Paper 2
What Waves in Matter covers
Waves in Matter is examined in Physics A Paper 2. It covers amplitude, wavelength, frequency and period; the wave equation; transverse and longitudinal waves; sound crossing a boundary: reflection, transmission and absorption; modelling waves with ripples and sound; electromagnetic waves as transverse, and energy transfer; frequency and wavelength across the spectrum; what our eyes detect, and light as an electromagnetic wave; uses of electromagnetic waves; hazards of ultraviolet, X-rays and gamma rays; ray diagrams for reflection and refraction; and how colour arises.
Where it is assessed
Paper 2
Physics A Paper 2: 1 hour 45 minutes, 90 marks, 50% of the GCSE.
Check the OCR specification ↗The 12 subtopics
Each one has its own page.
- Amplitude, wavelength, frequency and periodAmplitude, period, wavelength and frequency and their units, the link between period and frequency with calculations, how amplitude relates to energy, how a point in a material moves as a wave passes, and measuring the wavelength of a longitudinal wave.Open →
- The wave equationWave velocity = frequency × wavelength and its units, why a higher frequency means a shorter wavelength at a fixed speed, pitch and wavelength in air, finding velocity from distance and time, and calculations of velocity, frequency and wavelength for sound, water and radio waves.Open →
- Transverse and longitudinal wavesHow the direction of vibration differs in transverse and longitudinal waves, crests and troughs, compressions and rarefactions, an example of each type, and what the two types have in common.Open →
- Sound crossing a boundary; reflection, transmission and absorptionWhich property of sound stays the same across a boundary, why wavelength changes, wavelength calculations in air and water, what reflection, transmission and absorption mean, and ultrasound and sonar uses.Open →
- Modelling waves with ripples and soundWhy ripples model transverse waves and sound longitudinal ones, methods for measuring the speed of ripples and of sound, and the evidence that waves transfer energy without moving matter along.Open →
- Electromagnetic waves as transverse, and energy transferElectromagnetic waves as transverse waves that cross empty space at about 3 × 10⁸ m/s, why we can see the Sun but not hear it, and how infrared, microwaves, light, radio waves and ultraviolet transfer energy from a source to an absorber, including why a black car heats up faster.Open →
- Frequency and wavelength across the spectrumHow frequency and wavelength are related for electromagnetic waves, calculations using their common speed, the order of the spectrum, and which colours lie at each end of visible light.Open →
- What our eyes detect, and light as an electromagnetic waveThe narrow band of visible light the eye detects and the red and violet at its edges, why infrared and ultraviolet cannot be seen and how a thermal camera reveals infrared, and light as a transverse electromagnetic wave with the same speed as microwaves and a colour set by its wavelength.Open →
- Uses of electromagnetic wavesPractical uses of radio waves, microwaves, infrared, visible light, ultraviolet, X-rays and gamma rays, and why microwaves suit satellite links and light suits optical fibres.Open →
- Hazards of ultraviolet, X-rays and gamma raysEffects of too much ultraviolet on skin and how X-rays and gamma rays can harm the body.Open →
- Ray diagrams for reflection and refractionHow convex and concave lenses refract parallel rays, focal length, lenses for long and short sight, the law of reflection and the normal, the path of a ray through a glass block, and investigating reflection and refraction with a ray box, including the spectrum from a prism.Open →
- How colour arisesWhy a red jumper looks red in white light, why an object looks white and why an object looks black.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
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Give the units of wave velocity, frequency and wavelength, and explain why, of two notes in the same air, the lower has the longer wavelength.
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Compare the vibrations in transverse and longitudinal waves, name the high and low points of a transverse wave, and define a compression.
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Why do ripples model a transverse wave and sound, forming compressions and rarefactions, a longitudinal one, and how can the speed of ripples be timed?
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What are specular and diffuse reflection, and why can you see your face in a mirror but not in white paper?
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Roughly how does the speed of sound in air compare with the speed of ripples on water?
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What is meant by the amplitude of a wave?
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Sound travels faster in water than in air. What happens to its wavelength when it passes from air into water?
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Which has the higher frequency, a radio wave or an X-ray?
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Which part of the electromagnetic spectrum can the human eye detect?
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Which type of electromagnetic wave is used to communicate with satellites, and why is it suitable?
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Which three groupings of the electromagnetic spectrum are ionising?
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How does the shape of a convex lens differ from that of a concave lens?
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What is meant by the period of a wave?
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State in words the relationship between wave velocity, frequency and wavelength.
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In a transverse wave, how does the direction of vibration compare with the direction the wave travels?
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Explain why the wavelength of a sound changes when it crosses from one material into another.
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Explain why we can see the Sun but cannot hear it.
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Which has the longer wavelength, infrared or ultraviolet?
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Roughly how much of the whole electromagnetic spectrum can we see?
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Which type of electromagnetic wave carries telephone and internet signals along optical fibres?
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Which of infrared and ultraviolet is ionising, and what does the other one do instead?
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State the law of reflection.
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What is specular reflection?
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How is the period of a wave related to its frequency?
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What are the units of wave velocity, frequency and wavelength?
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In a longitudinal wave, how does the direction of vibration compare with the direction the wave travels?
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In which state of matter does sound normally travel fastest?
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Explain why ripples on water are used as a model of a transverse wave.
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In an electromagnetic wave, in what direction are the oscillations?
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Why is it enough to know the frequency of an electromagnetic wave in order to work out its wavelength?
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How can infrared radiation be detected if the eye cannot see it?
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What is meant by the normal at a surface?
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What is scattering, or diffuse reflection?
Take Waves in Matter further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Transverse wave vs Longitudinal wave
Transverse wave: vibrations at right angles to the direction of travel. Longitudinal wave: vibrations along the same line as the direction of travel.
Frequency vs Period
Frequency: number of complete waves passing a point each second. Period: time taken for one complete wave to pass a fixed point.
Compression vs Rarefaction
Compression: region where particles are pushed closer together, at higher pressure. Rarefaction: region where particles are spread further apart, at lower pressure.
Questions from this topic
Each one with the model answer underneath.
- 1
What is meant by the amplitude of a wave?
Model answer
The maximum displacement of a point on the wave from its undisturbed rest position.
- 2
What is meant by the period of a wave?
Model answer
The time taken for one complete wave to pass a fixed point.
- 3
How is the period of a wave related to its frequency?
Model answer
The period is one divided by the frequency, so the two are reciprocals of each other.
- 4
A wave completes one full oscillation every 0.02 s. What is its frequency?
Model answer
Its frequency is 50 Hz, because 1 ÷ 0.02 = 50.
- 5
A wave has a frequency of 200 Hz. What is its period?
Model answer
Its period is 0.005 s, because 1 ÷ 200 = 0.005.
- 6
How does the amplitude of a wave relate to the energy it transfers?
Model answer
A wave of larger amplitude transfers more energy.
What is inside Levo
Six ways to work the same material.
Waves in Matter revision questions
- What does Waves in Matter cover in OCR GCSE Physics A?
- 12 subtopics: amplitude, wavelength, frequency and period, the wave equation, transverse and longitudinal waves, sound crossing a boundary; reflection, transmission and absorption, modelling waves with ripples and sound, electromagnetic waves as transverse, and energy transfer, frequency and wavelength across the spectrum, what our eyes detect, and light as an electromagnetic wave, uses of electromagnetic waves, hazards of ultraviolet, x-rays and gamma rays, ray diagrams for reflection and refraction and how colour arises. Each one has its own page with questions and model answers.
- How is Waves in Matter organised?
- By the OCR J249 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Waves in Matter, 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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