plumiInterference, diffraction and gratings: OCR A‑Level Physics B questions
OCR A-Level Physics B past-paper questions on 4.1.2 Interference, diffraction and gratings, 2016–2025, with mark schemes and examiner’s reports where available.
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Q39(b)(i)
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All 75 questions on Interference, diffraction and gratings, as a list
- June 2025, Paper 1, Q39(b)(i) (3 marks): Use information from Fig. 39.2 and Fig. 39.3 to show that the wavelength of the microwaves is about 3 cm. [3]
- June 2025, Paper 1, Q39(b)(ii) (6 marks): Fig. 39.1 shows the apparatus used by a student to investigate the properties of microwaves. The microwaves from transmitter T are detected by the vertical meta
- June 2025, Paper 3, Q3(a)(i) (2 marks): Calculate the angle between the straight-through direction and the first order maximum. Angle = ° [2]
- June 2025, Paper 3, Q3(a)(ii) (2 marks): Calculate the number of lines per mm on the diffraction grating. Number of lines per mm = mm–1 [2]
- June 2025, Paper 3, Q3(b) (2 marks): Describe how you could determine a more accurate value for the number of lines per mm on the diffraction grating. [2]
- June 2025, AS Paper 1, Q20 (1 mark): A diffraction grating has n lines per cm and is illuminated with a laser emitting light of wavelength λ. The first order maximum is observed at an angle θ from
- June 2025, AS Paper 1, Q25(a) (1 mark): State one piece of evidence that light travels as waves. [1]
- June 2024, Paper 1, Q2 (1 mark): Which statement about ultrasound is correct? A Ultrasound can be diffracted and polarised. B Ultrasound can be diffracted but cannot be polarised. C Ultrasound
- June 2024, Paper 1, Q10 (1 mark): A beam of light from a hydrogen discharge lamp is incident normally on a diffraction grating with 4.50 × 105 lines per metre. What is the angle between the 410
- June 2024, Paper 2, Q4(a) (2 marks): Explain, using the concepts of path difference and phase, why a series of bright dots is seen across the screen. [2]
- June 2024, Paper 2, Q4(b)(i) (2 marks): Calculate the angle to the third order maximum. angle = ° [2]
- June 2024, Paper 2, Q4(b)(ii) (2 marks): Calculate the highest order of maximum that is produced using this apparatus. highest order of maximum = [2]
- June 2024, Paper 2, Q4(c) (4 marks): A student suggests the set-up shown in Fig. 4.2. Fig. 4.2 zinc surface positioned at third order maximum ultraviolet light grating source Electrons are ejected
- June 2024, Paper 2, Q8(a) (1 mark): The diameter of the primary mirror is 6.5 m. Show that the angular resolution limit of the telescope operating at a wavelength of 2000 nm is about 0.4 μrad. [1]
- June 2024, AS Paper 1, Q27(a) (1 mark): Complete the sentence: At spot X, the between waves from each part of the grating is one wavelength. [1]
- June 2024, AS Paper 1, Q27(b) (1 mark): There are 13 850 lines per cm across the DVD. Determine the separation, d, between the lines on the DVD. Write your answer in metres. Separation d = m [1]
- June 2024, AS Paper 1, Q27(d) (1 mark): One student suggests approximating the angle θ, between the centre and an outer spot on the screen using: θ ∼ s D State why this is not a good approximation in
- June 2024, AS Paper 1, Q27(e) (1 mark): Fig. 27.1c shows the experiment viewed from above. Fig. 27.1c first order maximum s θ grating centre spot 21.5 cm Show that the first-order maximum occurs at an
- June 2024, AS Paper 1, Q27(f) (2 marks): Calculate the wavelength of the laser light. Use the equation for the first-order diffraction maximum: λ = d sinθ Wavelength = nm [2]
- June 2024, AS Paper 2, Q6(b) (2 marks): The diagrams in Fig. 6.2 show identical sets of water waves moving towards different sized gaps in a barrier. Fig. 6.2 wave front Complete the diagrams in Fig.
- June 2024, AS Paper 2, Q6(c)(i) (3 marks): Calculate the wavelength of the light used in the experiment. wavelength = nm [3]
- June 2024, AS Paper 2, Q6(c)(ii) (2 marks): Describe how the pattern on the screen would change if a white light source was used instead of a monochromatic source. [2]
- June 2024, AS Paper 2, Q6(c)(iii) (6 marks): (iii)* The behaviour of light can be explained in terms of the wave model or the model of photons with a phasor amplitude. Describe how both the wave model of l
- June 2023, Paper 1, Q15 (1 mark): Red light of wavelength 670 nm is incident at right angles on a diffraction grating. A first order maximum is produced at 10°. Light of a different colour produ
- June 2023, AS Paper 1, Q22(b) (2 marks): Explain why the pattern on the fluorescent screen has light and dark regions. You may draw a diagram to support your answer. [2]
- June 2023, AS Paper 2, Q4(a)(i) (2 marks): State why the zero-order spectral line is a different colour from the other lines. [2]
- June 2023, AS Paper 2, Q4(a)(ii) (1 mark): State why the first-order blue spectral lines are closer to the zero-order line than the first-order red lines. [1]
- June 2023, AS Paper 2, Q4(b) (3 marks): Describe how the student could determine the wavelength of the blue light emitted by the discharge tube. [3]
- June 2022, Paper 1, Q32(a) (2 marks): Complete Fig. 32.2 to show diffraction of waves of the same wavelength through a narrower slit. Fig. 32.1 Fig. 32.2 [2]
- June 2022, Paper 1, Q32(b) (2 marks): Fig. 32.3 shows wavefronts after passing through a grating of many narrow slits. to bright line on screen Fig. 32.3 Use the diagram to explain why there is a br
- June 2022, AS Paper 1, Q5 (1 mark): A diffraction grating has three slits. An intensity maximum is produced on a distant screen where the phase difference between light from successive slits is 2π
- June 2022, AS Paper 2, Q8(a) (5 marks): Beth knows that, for small enough values of θ, the grating equation λ = d sin θ can be written λ = xd L which can be rearranged to x = ⎛⎞ λ d L. ⎝⎠ She measured
- June 2022, AS Paper 2, Q8(b) (4 marks): Jack chooses a different method based on single-slit diffraction. He has read that the diffraction pattern produced by waves of wavelength λ passing through a s
- June 2022, AS Paper 2, Q8(c) (6 marks): Two students are doing experiments to measure the wavelength of microwaves. Beth uses three sheets of aluminium to construct the double-slit arrangement shown i
- November 2021, Paper 1, Q22 (1 mark): Light of frequency f is incident normally on two slits in an opaque screen separated by a distance d. A pattern of maxima and minima is observed on a screen a d
- November 2021, Paper 2, Q10 (6 marks): 10* Explain how superposition is used by bats and in ultrasound scanners to increase the power of the ultrasound beam in a desired direction or location. You sh
- November 2021, Paper 3, Q2(a) (2 marks): Describe how the fringe separation could be measured in a school laboratory. [2]
- November 2021, Paper 3, Q2(b)(i) (3 marks): Calculate the wavelength of the light. wavelength = m [3]
- November 2021, Paper 3, Q2(c) (3 marks): The experiment is repeated using a red laser light instead of a filament bulb. Describe and explain the effect this will have on the experimental uncertainties.
- November 2021, AS Paper 1, Q20 (1 mark): In a double-slit experiment, the fringe spacing x is approximately given by x = Dλ d where D is the distance between the double-slit and the screen, d is the sl
- November 2021, AS Paper 1, Q22(a) (1 mark): What term is used to describe two light sources with a constant phase relationship? [1]
- November 2021, AS Paper 1, Q22(b) (1 mark): A diffraction grating is ruled with 250 lines per mm. Determine the spacing of the lines. line spacing = mm [1]
- November 2021, AS Paper 1, Q22(c) (3 marks): A laser emits light of wavelength 650 nm. The light is passed through a different diffraction grating with line spacing 5.0 × 10–6 m. Calculate the angle, in de
- November 2020, Paper 1, Q35(a) (2 marks): Explain why the intensity varies as it does. [2]
- November 2020, Paper 1, Q35(b) (3 marks): The first two maxima in signal occur at h = 0.123 m and 0.213 m. Use the data to calculate the wavelength λ of the microwaves. wavelength λ = m [3]
- November 2020, Paper 3, Q2(a) (2 marks): Light intensity is measured in W m–2, and can be calculated using the equation Intensity = E At where E is the radiant energy passing through a surface in time
- November 2020, AS Paper 1, Q14 (1 mark): Red laser light is diffracted through a single slit. When the slit width is increased, the diffraction pattern becomes A narrower and brighter. B narrower and d
- November 2020, AS Paper 2, Q5 (4 marks): A microscope slide coated with black paint has two thin lines scratched into the paint as shown in the figure. blackened slide clear scratched lines 0.2 mm apar
- November 2020, AS Paper 2, Q6(b)(i) (4 marks): The p.d. applied to the electron gun in Fig. 6.1 is gradually increased from 0, and diffraction orders produced by the above grating are seen on the fluorescent
- November 2020, AS Paper 2, Q6(b)(ii) (3 marks): Other diffraction patterns, not shown in Fig. 6.3, are produced by the graphite lattice. These are given by atom alignments in directions different from the one
- June 2019, Paper 2, Q4(b) (3 marks): Accelerated electrons can be diffracted by layers of graphite in a very similar way to light diffracted through a grating. When electrons are accelerated in a g
- June 2019, AS Paper 1, Q25(a) (1 mark): Explain the term coherent. [1] The pattern observed on the screen is shown in Fig. 25.2. A 14 cm Fig. 25.2 The point labelled A is completely dark. A is at a di
- June 2019, AS Paper 1, Q25(b) (2 marks): Show using the small angle approximation that this is 0.07 radian from the centre line. [2] 20 A is completely dark.
- June 2019, AS Paper 1, Q25(c) (2 marks): Explain why the path difference between two wavelets arriving at A from the top and bottom of the slit must be ½ λ. [2] The path difference between these two wa
- June 2019, AS Paper 1, Q25(d) (2 marks): Calculate the wavelength, in nm, of the light used. wavelength = nm [2] The screen is moved further away from the slit and the distance from the centre of the p
- June 2019, AS Paper 2, Q3 (3 marks): The comb shown in Fig. 3.1 has 53 teeth in a distance of 5.0 cm. It is mounted parallel to a wall 3.6 m away. Fig. 3.1 A laser emitting light of wavelength 630
- June 2018, Paper 1, Q38(c) (3 marks): Use the gradient to estimate an average wavelength for the light together with an uncertainty estimate. Make your method clear. wavelength = ± m [3]
- June 2018, Paper 2, Q8 (6 marks): 8* The upper surface of a solar cell is represented in Fig. 8.1. Use ideas about superposition of waves to explain why a transparent layer of silicon monoxide a
- June 2018, AS Paper 1, Q10 (1 mark): Light of wavelength 650 nm is incident at right angles on a diffraction grating with 300 lines per mm. What is the angle of the third-order maximum? A 4° B 11°
- June 2018, AS Paper 1, Q18 (1 mark): This experiment produces an interference pattern on the screen. empty tank monochromatic light source screen interference maxima double slit not to scale The ta
- June 2018, AS Paper 2, Q8(a)(iii) (3 marks): Describe how Alice and Bob could use the values obtained in part (a)(i) to find the mean frequency of the light from the LED. You do not need to do any calculat
- June 2017, Paper 2, Q9(b) (2 marks): An approximate value for the minimum resolvable angle θmin can be obtained from the wavelength of light equation θmin = diameter of pupil of the eye . The stude
- June 2017, AS Paper 1, Q13 (1 mark): The diagram shows plane wavefronts incident on a region X. The contents of region X are hidden from view. X Region X is most likely to contain … A a converging
- June 2017, AS Paper 1, Q28(a)(i) (1 mark): to locate position B precisely ��������������������������������������������������������������������������������������������������������������������������������
- June 2017, AS Paper 1, Q28(b)(i) (2 marks): Calculate the wavelength of the sound waves. Show how you arrive at your answer. wavelength = m [2]
- June 2017, AS Paper 1, Q28(d) (2 marks): The student now reverses the connections to speaker 2 but keeps the connections to speaker 1 unchanged. State and explain the effect this would have on the sign
- June 2017, AS Paper 2, Q1(a) (2 marks): Calculate the number of lines per millimetre, xxx. number of lines per millimetre = [2]
- June 2017, AS Paper 2, Q1(b) (2 marks): Yellow light of wavelength 583 nm is incident at right angles to the grating. Calculate the angle i2 of the second-order diffraction maximum. i2 = ° [2]
- June 2017, AS Paper 2, Q1(c) (2 marks): Explain why this yellow light has no third-order maxima. [2]
- June 2016, AS Paper 2, Q2(a) (2 marks): When the reflector is first put in position, it is observed that the microwave intensity recorded by the detector decreases. Explain this observation. [2]
- June 2016, AS Paper 2, Q2(b) (3 marks): The reflector is now moved gradually towards the source and detector, in the direction shown by the arrow on the reflector in Fig. 2. At y1, the detector readin
- June 2016, AS Paper 2, Q2(c) (2 marks): Describe and explain how the observations in this experiment, as the reflector is moved from y1 to y3, would be different if the experiment had used a source of
- June 2016, AS Paper 2, Q4(b)(i) (1 mark): The diffraction grating used had 1100 lines mm–1. Show that this corresponds to a grating spacing of about 9 × 10–7 m. [1]
- June 2016, AS Paper 2, Q4(b)(ii) (2 marks): Calculate the wavelength in nm of the light giving a first-order maximum at 32°. wavelength = nm [2]
- June 2016, AS Paper 2, Q4(b)(iii) (2 marks): Sketch the observed spectrum on the axes in Fig. 4.2. intensity 0 400 450 500 550 600 650 700 wavelength / nm Fig. 4.2 [2]
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