Waves and Quantum Behaviour | OCR A-Level Physics B (Advancing Physics) (H557)
Waves and Quantum Behaviour
- 179 questions
- 12 subtopics
- The physics content, examined on all three papers
- Component 01, Component 02 and Component 03
Waves and Quantum Behaviour 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 waves, phase and superposition, standing waves on strings, standing waves in air columns and the speed of sound, refraction, refractive index and Snell's law, two-slit interference, diffraction at a narrow aperture, the diffraction grating, measuring the wavelength of light, photons and the quantum E = hf, evidence that photons exchange energy in quanta, quantum behaviour: phasors and probability of arrival and electron diffraction and the de Broglie wavelength.
Sample questions from Waves and Quantum Behaviour
Answer each one closed book first, then open the answer.
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Waves, phase and superposition
Define the path difference between two waves arriving at the same point.
Show the answer
The path difference is the difference between the distances the two waves have travelled from their sources to that point. -
Standing waves on strings
What is the wavelength of the fifth harmonic on a string of length 1.2 m fixed at both ends?
Show the answer
The wavelength is 2L/n = 2 × 1.2/5 = 0.48 m. -
Refraction, refractive index and Snell's law
State Snell's law for light crossing a boundary between two media.
Show the answer
The ratio sin i / sin r equals the ratio of the speed of light in the first medium to the speed in the second, which for light entering a medium from air is the refractive index n. -
Two-slit interference
Two slits 0.50 mm apart are lit by light of wavelength 600 nm and the fringes are viewed 2.0 m away. What is the fringe spacing?
Show the answer
The spacing is x = λD/d = (6.00 × 10⁻⁷ × 2.0)/(5.0 × 10⁻⁴) = 2.4 × 10⁻³ m, which is 2.4 mm. -
The diffraction grating
A grating has 500 lines per millimetre. What is the spacing between adjacent slits?
Show the answer
The spacing is d = 1.00 × 10⁻³/500 = 2.00 × 10⁻⁶ m. -
Measuring the wavelength of light
State one safety precaution that must be taken when using a laser to measure wavelength.
Show the answer
The beam must never be directed towards anyone's eyes and should be stopped on a matt screen. -
Evidence that photons exchange energy in quanta
A metal has a work function of 2.0 eV. What is its threshold frequency?
Show the answer
The work function is 2.0 × 1.60 × 10⁻¹⁹ = 3.20 × 10⁻¹⁹ J, so f₀ = φ/h = 3.20 × 10⁻¹⁹ / 6.63 × 10⁻³⁴ = 4.8 × 10¹⁴ Hz. -
Quantum behaviour: phasors and probability of arrival
Why does the pattern building up one photon at a time show that arrival is probabilistic?
Show the answer
The point at which any individual photon lands cannot be predicted, only the chance of arrival at each point, which is given by the square of the resultant phasor there.
The 12 subtopics
One subtopic is one session. Work down the list.
| Subtopic | What it covers | Questions |
|---|---|---|
| Waves, phase and superposition | Recall questions on the principle of superposition, amplitude, phase and phase difference, path difference, coherent sources and why two lamps give no fringes, the path difference conditions for constructive and destructive interference, intensity and its link to amplitude, and v = fλ for sound. | 15 |
| Standing waves on strings | Recall questions on how standing waves form on a string, nodes and antinodes and their spacing, why no energy is transferred, displacement and phase within and between loops, fundamental and harmonic wavelengths, calculating wave speed, counting nodes, the effect of tension, why only certain frequencies resonate, and driving a string with a vibration generator. | 15 |
| Standing waves in air columns and the speed of sound | Recall questions on how an air column resonates, where nodes and antinodes fall, using two resonance positions rather than one, oscilloscope frequency measurements, and a closed tube's resonance ratio. | 15 |
| Refraction, refractive index and Snell's law | Recall questions on what changes and what stays the same as light enters glass, the wave explanation of bending, Snell's law calculations, ray-box measurements, and dispersion of colours. | 17 |
| Two-slit interference | Recall questions on the two-slit fringe pattern, why bright, dark and central fringes appear, why one source lights both slits, how slit separation, screen distance and colour change the fringe spacing, nλ = d sin θ and x = λD/d, the small-angle approximation, covering one slit, narrow slits, and white-light fringes. | 15 |
| Diffraction at a narrow aperture | Recall questions on when spreading at a gap is greatest, water waves through wide and narrow gaps, the single-slit pattern, angular spread, and why apertures limit a telescope or camera. | 13 |
| The diffraction grating | Recall questions on what a diffraction grating is and why its maxima are sharp, nλ = d sin θ and the order of a maximum, slit spacing from lines per millimetre, angles and the highest observable order, zero-order and white-light spectra, resolving close wavelengths, finding the slit spacing with sodium light, parallel beams, and overlapping orders. | 14 |
| Measuring the wavelength of light | Recall questions on the double-slit arrangement, why ten fringe spacings and a distant screen help, what limits accuracy, gratings and higher orders, angles measured both sides, and laser safety. | 13 |
| Photons and the quantum E = hf | Recall questions on photons and E = hf, the value of the Planck constant, E = hc/λ, the electronvolt and converting between joules and electronvolts, ultraviolet against infrared photons, X-ray photon energy, the photon rate from a laser, why light's energy arrives in quanta, and what sets a beam's brightness. | 14 |
| Evidence that photons exchange energy in quanta | Recall questions on threshold frequency, work function and φ = hf₀, the photoelectric equation hf = φ + Eₖ(max) and calculations with it, why intense light below threshold frees no electrons, why the wave model fails, line emission spectra, determining the Planck constant with LEDs, and the limits of the particle and wave models of light. | 17 |
| Quantum behaviour: phasors and probability of arrival | Recall questions on phasors and their rate of rotation, probability of arrival from the resultant phasor, trip time and phasor direction, why light travels in straight lines, paths of stationary time, bright and dark two-slit fringes, photons arriving one at a time, blocking alternate zones, wide slits, and how phasors avoid choosing between wave and particle. | 16 |
| Electron diffraction and the de Broglie wavelength | Recall questions on the ring pattern from graphite and what it shows, de Broglie wavelengths of electrons, protons and everyday objects, the effect of accelerating voltage, and microscope resolution. | 15 |
How the guide is worked
Answering a question from memory stores it far better than reading the answer again. The guide runs that as a fixed procedure on one subtopic at a time, about twenty minutes a session.
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Step 1 · Closed book
Cover the answers. Work through one subtopic and write down what you can. Leave blanks where you have nothing.
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Step 2 · Open book
Go back to the top. Read each printed answer and write it out in full, including the ones you had right.
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Step 3 · Closed book again
Same questions, same order, from memory. The gap between pass one and pass three is the session result.
Read the full method, the return schedule and the research behind it.
Nearby topics
OCR A-Level Physics B (Advancing Physics) Active Recall Guide
Every topic, not just this one. 2,455 questions with their answers.