Polarisation, diffraction and de Broglie: Edexcel International A Level Physics questions

Every Edexcel International A Level Physics exam question on Polarisation, diffraction and de Broglie (specification points 49–54), 2019–2025, with its mark scheme and examiner’s report.

All 95 questions on Polarisation, diffraction and de Broglie, as a list

June 2025, AS Unit 2, Q12(b)(i) (3 marks): Explain the difference between unpolarised light and polarised light. (3)
June 2025, AS Unit 2, Q12(b)(ii) (3 marks): The student uses a polarising filter to view the light reflected by the glass block. Explain what she would observe as she rotates the filter. (3)
June 2025, AS Unit 2, Q15(a) (2 marks): State what is meant by diffraction. (2)
June 2025, AS Unit 2, Q15(b)(i) (4 marks): Show that the de Broglie wavelength for the electron is about 1.8 × 10 –11 m. (4)
June 2025, AS Unit 2, Q15(b)(ii) (3 marks): A student suggests that the beam of electrons would produce a diffraction pattern if a diffraction grating with 5000 lines per cm was used. screen electron beam
January 2025, AS Unit 2, Q11 (3 marks): An electron is moving with velocity 3.6 × 10 7 m s –1. Calculate the de Broglie wavelength of this electron. de Broglie wavelength =
January 2025, AS Unit 2, Q14(b)(i) (4 marks): Calculate the number of lines per mm on the diffraction grating. λ = 650 nm L = 1.30 m x = 0.22 m (4) Number of lines per mm =
January 2025, AS Unit 2, Q14(b)(ii) (3 marks): Explain how a first order maximum is produced on the screen. (3)
January 2025, AS Unit 3, Q4(a)(i) (2 marks): Complete the table with corresponding values of sin θ. Use the additional column to record your processed data. (2)
January 2025, AS Unit 3, Q4(a)(ii) (5 marks): Plot a graph of f on the y-axis against sin θ on the x-axis on the grid opposite. (5)
January 2025, AS Unit 3, Q4(b) (2 marks): The student derived the following formula v λ θ sin f where λ is the wavelength of the laser light and v is the speed of sound in the liquid. Explain how a grap
January 2025, AS Unit 3, Q4(c)(i) (3 marks): Determine the value of v using your graph. λ = 650 nm (3) v =
January 2025, Unit 4, Q14(b) (4 marks): In one cathode ray tube, the electrons in the beam had a de Broglie wavelength –11 m. of 2.65 × 10 Calculate the potential difference V required to accelerate t
October 2024, AS Unit 2, Q7 (1 mark): Particle X of mass m is moving with velocity v and has a de Broglie wavelength λ. Particle Y has a de Broglie wavelength 0.25 λ. Which row of the table could gi
October 2024, AS Unit 2, Q11 (2 marks): A beam of electrons passes through a thin layer of graphite. The electrons are then incident on a fluorescent screen, causing a series of rings to form, as show
October 2024, AS Unit 2, Q16(a) (1 mark): Give one safety precaution the student should take during the experiment. (1)
October 2024, AS Unit 2, Q16(b) (2 marks): State what measurements the student should make to determine the wavelength of the light from the laser. (2)
October 2024, AS Unit 2, Q16(c)(i) (4 marks): Show that the wavelength of the light from the laser is about 600 nm. (4)
October 2024, AS Unit 2, Q16(c)(ii) (2 marks): The student observed maxima beyond the first order. Determine the greatest order of maximum that the student could observe. (2) Greatest order of maximum =
June 2024, AS Unit 2, Q4 (1 mark): Which of the following is evidence that electrons can behave like waves? A Electrons are attracted towards positively charged objects. B Electrons can absorb ph
June 2024, AS Unit 2, Q11 (3 marks): A student wearing polarising sunglasses observes a mobile phone screen. The student rotates the mobile phone through 90°, as shown. The screen then appears comp
June 2024, AS Unit 2, Q12(a) (2 marks): In the visible spectrum formed on the screen, violet light is closest to the central maximum and red light is furthest away. Explain why the violet light is clo
June 2024, AS Unit 2, Q12(b) (2 marks): The diffraction grating has a line spacing of 1.62 × 10 Calculate the wavelength of the violet light. (2) Wavelength of the violet light =
June 2024, AS Unit 2, Q17(b)(ii) (2 marks): Calculate the de Broglie wavelength of electrons moving at 5.3 × 10 (2) de Broglie wavelength =
January 2024, AS Unit 2, Q3 (1 mark): An electron has a de Broglie wavelength of 3.5 × 10 –10 m. –1? Which of the following expressions gives the velocity of the electron in m s 34 6 63 . 10 A 31 10
January 2024, AS Unit 2, Q9 (1 mark): Two polarising filters, X and Y, are arranged between a light source and an observer as shown. light source observer Y X The intensity of light reaching the obs
January 2024, AS Unit 2, Q17(a) (2 marks): Describe how Huygens’ construction can be used to predict the shape of diffracted wavefronts. (2)
January 2024, AS Unit 2, Q17(b) (6 marks): The wavefronts in the sea arrive parallel to the harbour wall. The wavelength of the waves varies as the weather varies. There are identical boats at two positi
January 2024, AS Unit 3, Q3(b)(i) (2 marks): The student used a metre rule to measure the distance between adjacent minima. Describe how the student should determine an accurate value for the distance betw
January 2024, AS Unit 3, Q3(b)(ii) (2 marks): Explain how the student could modify the arrangement of the apparatus to reduce the percentage uncertainty in this value. (2)
January 2024, Unit 4, Q15 (4 marks): A beam of electrons was directed through a thin piece of graphite towards a fluorescent screen, using the apparatus shown. vacuum cathode anode fluorescent scre
October 2023, AS Unit 2, Q1 (1 mark): The formula for a diffraction grating in the list of equations is nλ = d sin θ. Which of the following quantities does not have units? A n B λ C d D θ
October 2023, AS Unit 2, Q10 (1 mark): Two photographs, X and Y, were taken of the same car windscreen. Photograph Y was taken through a polarising filter. Photograph X Photograph Y (Source: © Etan J
October 2023, AS Unit 2, Q15(a) (4 marks): This demonstration can be used to make conclusions about the behaviour of the electrons and the structure of the graphite. State these conclusions. (4)
October 2023, AS Unit 2, Q15(b)(ii) (2 marks): Calculate the maximum velocity of the electrons. (2) Maximum velocity =
October 2023, AS Unit 2, Q15(b)(iii) (3 marks): The accelerating p.d. was then increased. Explain how the pattern on the screen would change. (3)
October 2023, Unit 4, Q12 (3 marks): An electron has kinetic energy 7.2 × 10 –16 J. Calculate the de Broglie wavelength of the electron. Wavelength =
June 2023, AS Unit 2, Q1 (1 mark): Waves may spread out as they pass an object. Which of the following is the name of this process? A diffraction B interference C reflection D refraction
June 2023, AS Unit 2, Q5 (1 mark): An electron has a de Broglie wavelength of 1.55 × 10 −9 m. Which of the following gives the speed, in m s −1, of this electron? 31 9 11 . 10 A 34 9 6 63 . 10 1
June 2023, AS Unit 2, Q8 (1 mark): Light from a laser is incident on a diffraction grating, causing a series of maxima to be seen on a screen. The positions of the central maximum and first order
June 2023, AS Unit 2, Q13(b)(i) (3 marks): Explain the difference between unpolarised and plane polarised light. (3)
June 2023, AS Unit 2, Q13(b)(ii) (2 marks): Reducing the intensity of the reflected light would help the observer see the fish. Explain how the observer can use a polarising filter to reduce the intensity
June 2023, AS Unit 3, Q3(a)(i) (2 marks): Give two reasons why vernier calipers are more appropriate for these measurements than a transparent ruler. (2)
June 2023, AS Unit 3, Q3(a)(ii) (2 marks): Describe how the student should measure the diameter of a ring as accurately as possible. (2)
June 2023, AS Unit 3, Q3(b)(i) (2 marks): Determine the mean value of a in m (2) Mean value of a = m 2 V
June 2023, AS Unit 3, Q3(b)(iii) (2 marks): A different student repeated the investigation using six values of V. She plotted a 1 graph of V against 2 and determined the constant a from the gradient. λ Gi
June 2023, AS Unit 3, Q3(c)(i) (2 marks): Calculate the value of h, in J s, when a is 1.46 × 10 (2) h = J s
June 2023, AS Unit 3, Q3(c)(ii) (2 marks): The percentage uncertainty in the calculated value of h is 6%. Comment on the accuracy of your calculated value of h. (2)
January 2023, AS Unit 2, Q4 (1 mark): The equation nλ = d sin θ can be used to determine the wavelength of laser light that has passed through a diffraction grating. Which of the following is repres
January 2023, AS Unit 2, Q11 (3 marks): A particle travelling at a speed of 9.89 × 10 5 m s –1 has a de Broglie wavelength of 7.37 × 10 –10 m. Deduce whether this particle has a mass equal to the elec
January 2023, AS Unit 2, Q16(b)(i) (3 marks): Explain the difference between unpolarised light and plane polarised light. (3)
January 2023, AS Unit 2, Q16(b)(ii) (2 marks): Describe how a student can demonstrate that light from the Sun is unpolarised. (2)
January 2023, Unit 4, Q17(b) (3 marks): In 1927 J J Thomson’s son directed beams of electrons at thin films of metal. The photograph shows one of the patterns observed. Explain how this pattern change
October 2022, AS Unit 2, Q8 (1 mark): A ray of light is incident on a glass block, as shown. Which of the following does not occur when the ray of light is incident on the glass block? A diffraction
October 2022, AS Unit 2, Q11 (3 marks): A beam of electrons is directed at a thin metal foil. After passing through the foil the electrons are detected by a fluorescent screen. The image shows the pat
October 2022, AS Unit 2, Q18(a) (2 marks): Calculate the angle θ2 . (2) θ2 =
October 2022, AS Unit 2, Q18(b) (3 marks): The student measured θ for values of n from 1 to 4. Describe how a graphical method can be used to determine the wavelength of the light from the laser. Assume
October 2022, AS Unit 2, Q18(c) (4 marks): In a separate experiment, the student uses a different diffraction grating that has been labelled as “300 lines per mm” by another student. The distance measure
June 2022, AS Unit 2, Q4 (1 mark): A ray of unpolarised light is incident on a polarising filter. The polarising filter transmits light of intensity I, as shown. rotation I polarising filter The
June 2022, AS Unit 2, Q5 (1 mark): A laser, diffraction grating and screen are set up as shown. The position of the central maximum is O and the position of the first order maximum is X. The diff
June 2022, AS Unit 2, Q10 (1 mark): In 1927, G P Thomson first demonstrated that electrons passing through a nickel crystal produce a diffraction pattern. Which of the following can be concluded f
June 2022, AS Unit 2, Q17(b) (6 marks): The ultraviolet (UV) section of the electromagnetic spectrum can be split into three parts, known as UVA, UVB and UVC. The range of wavelengths of these parts i
January 2022, AS Unit 2, Q2 (1 mark): The de Broglie wavelength for a moving electron is 5.47 × 10–10 m. Which of the following expressions gives the speed of the electron in m s–1? × − ( . 6 63 10
January 2022, AS Unit 2, Q14(a) (4 marks): The diagram below shows the position of the central dot at O. The next bright dot appears at position X. The diffraction grating has 450 lines per mm. X 0.500 m
January 2022, AS Unit 2, Q14(b) (3 marks): Explain why a series of bright dots is seen on the screen. (3)
January 2022, AS Unit 2, Q14(c) (2 marks): The laser is replaced by a source producing a parallel beam of bright white light. Suggest what would now be observed on the screen. (2)
January 2022, AS Unit 2, Q16(c) (2 marks): The light emerging from prism B is observed through a polarising filter. The polarising filter is rotated gradually, and the light transmitted by the filter var
October 2021, AS Unit 2, Q2 (1 mark): A student determines the wavelength of the light emitted by a laser. She uses the laser, a diffraction grating and a screen. Which of the following measurements
October 2021, AS Unit 2, Q9 (1 mark): The wavefront diagrams show consecutive waves approaching gaps of different sizes. A B C D The wavefronts diffract as they pass through each gap. In which diagr
June 2021, AS Unit 2, Q5 (1 mark): A moving electron has a de Broglie wavelength of 656 nm. Which of the following could be used to determine the speed of the electron? 34 6 63 . 10 A 9 31 ( 656
June 2021, AS Unit 2, Q16(a) (3 marks): Explain the difference between unpolarised and plane polarised light. (3)
June 2021, AS Unit 2, Q16(b) (3 marks): An unpolarised light source is directed towards a screen. The intensity of radiation measured at the screen is 1.00 W m−2. Two polarising filters are placed bet
June 2021, AS Unit 2, Q16(c) (3 marks): Polarisation can be used to identify when some materials are under stress. Placing the material under stress causes the plane of polarisation of the light passi
June 2021, Unit 4, Q5 (1 mark): The diagram represents an arrangement to demonstrate electron diffraction. anode hot filament fluorescent screen θ θ – + V vacuum sample A beam of electrons is
January 2021, AS Unit 2, Q9 (1 mark): In 1924 de Broglie suggested that electrons have wave properties. The de Broglie equation states: h λ = p Which of the following is correct? A The de Broglie wa
January 2021, AS Unit 2, Q18(a) (2 marks): Describe how the teacher can demonstrate that the light from the laser pointer is plane polarised. (2)
January 2021, AS Unit 2, Q18(b)(i) (1 mark): The diffraction grating equation is nλ = d sin θ State the quantity represented by d. (1)
January 2021, AS Unit 2, Q18(b)(ii) (3 marks): The teacher made the following measurements: distance from central maximum to first order maximum = 1.61m distance from diffraction grating to screen = 2.74 m T
January 2021, AS Unit 2, Q18(b)(iii) (3 marks): Using this diffraction grating and laser pointer, only the first order maxima and the central maximum are produced. Explain how the teacher, using the same lase
October 2020, AS Unit 2, Q3 (1 mark): A diffraction grating has 300 lines per mm. When laser light is directed towards the diffraction grating, a diffraction pattern is observed on a screen. The pos
October 2020, AS Unit 2, Q8 (1 mark): Which of the following statements about waves is correct? A Both longitudinal and transverse waves can be polarised. B Neither longitudinal nor transverse waves
October 2020, AS Unit 2, Q15(b) (5 marks): The Bohr model can also be used to predict an approximate radius for an atom. The equation for the radius r of the hydrogen atom is: = h k 2 r πme 2 where m = m
January 2020, AS Unit 2, Q2 (1 mark): Which of the following describes the oscillations in polarised waves? A in a single plane which is perpendicular to the direction of wave travel B in many plane
January 2020, AS Unit 2, Q9 (1 mark): In an experiment, laser light is shone through a diffraction grating so that a series of bright dots appears on a screen. The equation nλ = d sin θ can be used
January 2020, AS Unit 2, Q10 (1 mark): The evidence for the wave nature of electrons came from experiments involving A diffraction. B polarisation. C reflection. D refraction.
January 2020, AS Unit 2, Q16(a) (2 marks): Explain, using Huygens’ construction, how diffraction occurs as waves pass through a gap. (2)
January 2020, AS Unit 2, Q16(b) (3 marks): The diffraction pattern consists of a central bright spot surrounded by concentric circles of light of decreasing intensity. A close‑up of the pattern is shown
June 2019, AS Unit 2, Q2 (1 mark): A filament lamp is a source of unpolarised light. A polarising filter is placed between a filament lamp and an observer. The filter is rotated in the plane perp
June 2019, AS Unit 2, Q4 (1 mark): Which of the following has the largest de Broglie wavelength? A an electron travelling at 3.0 × 105 m sí B an electron travelling at 4.0 × 105 m sí C a neutro
June 2019, AS Unit 2, Q16(c) (3 marks): Light from the tube was directed through a diffraction grating, labelled as having 300 lines per mm. The diffraction pattern produced was displayed on a flat sc
June 2019, AS Unit 3, Q3(a) (4 marks): Describe how the student can accurately determine the radius of the first bright ring of the diffraction pattern. (4)
June 2019, AS Unit 3, Q3(b) (2 marks): Explain how the diffraction pattern provides evidence for the wave nature of electrons. (2)
June 2019, AS Unit 3, Q3(c)(ii) (6 marks): Use the results in the table to plot a graph of λ on the y-axis against sin θ on the x-axis on the grid provided. Use the right-hand column of the table for you
June 2019, AS Unit 3, Q3(c)(iii) (3 marks): Determine the gradient of the graph. (3) Gradient =
June 2019, AS Unit 3, Q3(c)(iv) (2 marks): The diffraction occurs as the electrons pass through the thin slice of graphite. The atoms in the graphite are arranged in layers. The position of the rings in

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