Key term
CCEA A-Level Physics 1210
Physical Quantities, Scalars and Vectors
Moments and Equilibrium
Linear Motion and Dynamics
Newton's Laws of Motion
Linear Momentum and Impulse
Work, Energy and Power
Current, Charge and Potential Difference
Resistance and Resistivity
Topic overviewResistance and Ohm's lawOhmic and non-ohmic behaviourResistors in series and in parallelInvestigating current, voltage and resistance in series and parallel circuitsElectrical power and energy in resistive circuitsResistivity and the equation R = ρl/AMeasuring the resistivity of a metalCurrent–voltage characteristics of a conductor, a lamp and a diodeResistance, temperature and superconductivity
Internal Resistance and Potential Dividers
Topic overviewInternal resistance and terminal potential differenceConsequences of internal resistance for external circuitsMeasuring electromotive force and internal resistanceThe potential divider and variable outputPotential dividers in lighting and heating control circuitsLoaded potential dividers and output voltage calculations
Waves
Refraction
Lenses
Superposition, Interference and Diffraction
Topic overviewSuperposition of wavesStanding waves, nodes and antinodesStanding waves on stretched stringsStanding waves in a pipe closed at one endMeasuring the speed of sound with a resonance tubeConditions for observable interferencePath difference and phase differenceYoung's double slitDiffraction at a single slitThe diffraction grating
Quantum Physics
Wave-Particle Duality
Astronomy
Practical Skills and Data Analysis
Topic overviewChoosing and using measuring instrumentsPrecision, accuracy and recording measurementsUsing the cathode ray oscilloscope to measure voltage and frequencyTables, graphs and presenting resultsLinearising a relationship and using the gradientAbsolute and percentage uncertaintyCombining uncertainties and uncertainty on a graphRandom and systematic error, reliability and refining an experiment
Deformation of Solids
Thermal Physics
Topic overviewBoyle's law, Charles's law and the pressure lawThe ideal gas equation pV = nRTThe Avogadro constant, the mole and pV = NkTInternal energy and the distribution of molecular energyThe kinetic theory equation pV = ⅓Nm⟨c²⟩Average molecular kinetic energy and temperatureAbsolute zero and the kelvin scaleSpecific heat capacity and the electrical method
Uniform Circular Motion
Simple Harmonic Motion
Topic overviewDefining simple harmonic motion and a = −ω²xDisplacement, velocity and acceleration: x = A cos ωtThe simple pendulum and T = 2π√(l/g)The loaded spiral spring and T = 2π√(m/k)SHM graphs and finding velocity from a gradientFree vibrations, forced vibrations and resonanceDamping: light, critical and over-damping
The Nucleus and Radioactive Decay
Topic overviewAlpha-particle scattering and the nuclear atomNuclear radius and nucleon numberThe density of nuclear matterAlpha, beta and gamma radiation: nature, penetration and rangeNuclear equations and changes in nucleon and proton numberThe random and exponential nature of radioactive decayActivity, the decay constant and A = −λNExponential decay calculations with A = A₀e^(−λt)Half-life and measuring it
Nuclear Energy, Fission and Fusion
Gravitational Fields
Electric Fields
Capacitors
Magnetic Fields
Charged Particles and Accelerators
Superposition, Interference and Diffraction
- 10 subtopics
- 30 things to know
- Unit AS 2
What Superposition, Interference and Diffraction covers
Superposition, Interference and Diffraction is examined in Unit AS 2, Waves, Photons and Astronomy, and drawn on again in Unit AS 3, Practical Techniques and Data Analysis. It covers superposition of waves, standing waves, nodes and antinodes, standing waves on stretched strings, standing waves in a pipe closed at one end, measuring the speed of sound with a resonance tube, conditions for observable interference, path difference and phase difference, Young's double slit, diffraction at a single slit and the diffraction grating.
Where it is assessed
Unit AS 2
Waves, Photons and Astronomy, and again in Unit AS 3, Practical Techniques and Data Analysis.
Check the CCEA specification ↗The 10 subtopics
Each one has its own page.
- Superposition of wavesPrinciple of superposition, graphical addition of two waves and constructive interference.Open →
- Standing waves, nodes and antinodesStanding wave and distance between a node and the antinode next to it.Open →
- Standing waves on stretched stringsRecall questions on the positions of the nodes and antinodes in each mode, the wavelength of the simplest mode in terms of the string length and the general expression, the lowest frequency, worked calculations on strings of given length and wave speed, and the effects of tension, thickness and fretting.Open →
- Standing waves in a pipe closed at one endRecall questions on why there is a node at the closed end and an antinode at the open end, the wavelength of the simplest mode as four times the length, why only odd multiples of the lowest frequency resonate, worked frequency calculations, the effect of warming the air, and the node and antinode counts in higher modes.Open →
- Measuring the speed of sound with a resonance tubeEnd correction in a resonance tube experiment and two sources of uncertainty in a resonance tube experiment.Open →
- Conditions for observable interferenceRecall questions on what interference is and what coherence means, why the sources must have the same frequency and a constant phase relationship, why similar amplitudes and the same polarisation matter, why two filament lamps will not do, how coherent sources are obtained in practice, and what white light produces.Open →
- Path difference and phase differenceRecall questions on the definition of path difference, the whole-wavelength and half-odd-wavelength conditions for constructive and destructive interference, the same conditions in terms of phase, why the central fringe is always bright, worked examples with given path differences, and two loudspeakers wired out of phase.Open →
- Young's double slitRecall questions on the experiment and what is seen on the screen, the equation λ = ay/d with every symbol, why the slits must be close and the screen far, worked wavelength and fringe-spacing calculations, the effect of changing the slit separation, the screen distance and the colour, and why several fringes are measured at once.Open →
- Diffraction at a single slitRecall questions on what diffraction is and the pattern a single slit produces, how the central band compares with the others in width and brightness, the effect of narrowing the slit or changing the wavelength, why sound diffracts round a doorway but light does not, the ripple tank demonstration, and the limit diffraction sets on a telescope.Open →
- The diffraction gratingRecall questions on what a grating is and the equation d sin θ = nλ, calculating the grating spacing from lines per millimetre, what the order number means, worked angle and wavelength calculations, why grating beams are sharper than double-slit fringes, measuring the angle on both sides, and the white-light spectra a grating produces.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Numbers
The nodes of a standing wave are 0.30 m apart and the vibration frequency is 250 Hz. Calculate the speed of the progressive waves.
Numbers
A string 1.0 m long fixed at both ends vibrates with three nodes and two antinodes. Calculate the wavelength.
Numbers
A string 0.80 m long carries waves at 240 m s⁻¹. Calculate its lowest vibration frequency.
Numbers
A pipe closed at one end is 0.25 m long and the speed of sound is 340 m s⁻¹. Calculate its lowest resonant frequency.
Numbers
A pipe closed at one end is 0.170 m long and the speed of sound is 340 m s⁻¹. Calculate its lowest resonant frequency.
Key term
Describe an experiment to measure the speed of sound in air using a resonance tube.
Numbers
A tuning fork of frequency 440 Hz gives resonance at air column lengths of 0.185 m and 0.560 m. Calculate the speed of sound.
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Why is a tuning fork preferred to a whistle or the human voice as the source in a resonance tube experiment?
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Why must two sources be coherent for an interference pattern to be observed?
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Why should the two sources in an interference experiment have similar amplitudes?
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Why is monochromatic light used in an interference experiment?
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Describe Young's slits experiment for measuring the wavelength of monochromatic light.
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Why must the two slits be very close together in Young's experiment?
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How is the requirement for coherent sources met in Young's slits experiment with a lamp?
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Why can sound be heard round the corner of an open doorway while light cannot be seen round it?
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State the diffraction grating equation, defining every symbol with its unit.
Numbers
Light of wavelength 600 nm passes through a grating with 300 lines per millimetre. Calculate the angle of the first order beam.
Numbers
Light of wavelength 500 nm passes through a grating with 600 lines per millimetre. Calculate the angle of the second order beam.
Key term
State the condition on path difference for constructive interference.
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Two waves of amplitude 3.0 cm meet in phase. State the amplitude of the resultant.
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Express the wavelength of the simplest standing wave on a string of length L fixed at both ends.
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State the condition on path difference for destructive interference.
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What is diffraction?
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Two waves of amplitude 3.0 cm meet exactly in antiphase. State the amplitude of the resultant.
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State the conditions required for a standing wave to be produced.
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Express the wavelength of the third possible mode of vibration of a string of length L fixed at both ends.
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Why is there an antinode at the open end of a pipe?
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State the conditions for constructive and destructive interference in terms of phase difference.
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How does the width of the central bright band of a single slit pattern compare with that of the bands beside it?
Take Superposition, Interference and Diffraction further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Coherent vs In phase
Coherent: the relationship between the two oscillations stays the same as time passes, whatever its value. In phase: that relationship is specifically zero.
Questions from this topic
Each one with the model answer underneath.
- 1
State the principle of superposition.
Model answer
When two or more waves meet at a point, the resultant displacement at that point is the vector sum of the displacements each wave would produce there on its own.
- 2
What is meant by the graphical addition of two waves?
Model answer
The two wave shapes are drawn on the same axes and, at every position along the axis, the two displacements are added together taking their signs into account, and the resulting values are joined up to give the resultant wave.
- 3
Two waves of amplitude 3.0 cm meet in phase. State the amplitude of the resultant.
Model answer
The resultant amplitude is 3.0 + 3.0 = 6.0 cm, because the displacements are in the same direction at every instant.
- 4
Two waves of amplitude 3.0 cm meet exactly in antiphase. State the amplitude of the resultant.
Model answer
The resultant amplitude is zero, because the two displacements are always equal and opposite and cancel completely.
- 5
A wave of amplitude 5.0 cm meets a wave of amplitude 3.0 cm in antiphase. State the amplitude of the resultant.
Model answer
The resultant amplitude is 5.0 − 3.0 = 2.0 cm, and the resultant is in phase with the larger of the two waves.
- 6
Define constructive interference.
Model answer
Constructive interference occurs where waves meet in phase, so that their displacements add and the resultant amplitude is larger than that of either wave alone.
What is inside Levo
Six ways to work the same material.
Superposition, Interference and Diffraction revision questions
- What does Superposition, Interference and Diffraction cover in CCEA A-Level Physics?
- 10 subtopics: superposition of waves, standing waves, nodes and antinodes, standing waves on stretched strings, standing waves in a pipe closed at one end, measuring the speed of sound with a resonance tube, conditions for observable interference, path difference and phase difference, young's double slit, diffraction at a single slit and the diffraction grating. Each one has its own page with questions and model answers.
- How is Superposition, Interference and Diffraction organised?
- By the CCEA 1210 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Superposition, Interference and Diffraction, 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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