Lesson 3.3.2.2

3.3.2.2 Diffraction Quiz: AQA Physics, Unit 3

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 3.3.2.2, Diffraction: 20 multiple choice questions for the AQA Physics (7408), Unit 3: Waves, written with Revision Ninja.

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The 20 questions

  1. What is diffraction?

    • The absorption of waves by a medium
    • The reflection of waves from a smooth surface
    • The spreading of waves as they pass through a gap or around an obstacle
    • The bending of waves caused by a change of speed

  2. When is diffraction most noticeable?

    • When the wave has zero frequency
    • When the wave is reflected
    • When the gap width is comparable to the wavelength
    • When the gap is much wider than the wavelength

  3. What is seen in the single-slit diffraction pattern with white light?

    • A central maximum with coloured fringes at the sides
    • Equal bands of all colours
    • Only one black band
    • A pattern of dots

  4. What happens to the width of the central diffraction maximum when the slit is made narrower?

    • It becomes wider
    • It is unchanged
    • It disappears completely
    • It becomes narrower

  5. What is the diffraction grating equation for maxima at normal incidence?

    • d sin(theta) = n λ
    • d sin(theta) = λ/n
    • d = n λ sin(theta)
    • d cos(theta) = n λ

  6. What quantity determines the angular separation of orders for a grating?

    • the colour of the grating
    • the mass of the grating
    • the slit spacing d and the wavelength
    • the temperature of the grating

  7. Which is a common application of diffraction gratings?

    • charging capacitors
    • amplifying the intensity of sound
    • cooling electronic components
    • separating wavelengths in spectroscopy

  8. A grating has spacing d = 2.0 μm. What is the angle of the first-order maximum for λ = 500 nm?

    • 14.5 degrees
    • 7.2 degrees
    • 30 degrees
    • 45 degrees

  9. A grating has spacing d = 2.0 μm. What is the angle of the second-order maximum for λ = 400 nm?

    • 23.6 degrees
    • 0.4 degrees
    • 47.2 degrees
    • 11.5 degrees

  10. A grating has spacing d = 2.0 μm. What is the highest order visible for λ = 700 nm?

    • 4
    • 1
    • 2
    • 3

  11. A grating has spacing d = 1.0 μm. What is the first-order angle for λ = 500 nm?

    • 30 degrees
    • 45 degrees
    • 15 degrees
    • 60 degrees

  12. What happens to the central maximum of a single slit if the slit width is doubled?

    • It doubles in intensity only
    • It becomes narrower
    • It is unchanged
    • It becomes wider

  13. A grating has spacing d = 2.0 μm. A first-order maximum is seen at 20 degrees. What is the wavelength?

    • 684 nm
    • 1.00 μm
    • 342 nm
    • 6.8 nm

  14. Why are the maxima produced by a diffraction grating sharper than the single-slit pattern?

    • Only one slit transmits light
    • The grating absorbs most of the light
    • The grating increases the wavelength
    • Many slits reinforce at specific angles, producing narrow bright maxima

  15. Why is sound diffracted around corners more than light is?

    • Sound cannot be diffracted at all
    • Its wavelength is much longer and comparable to obstacles
    • Sound travels faster than light
    • Sound has a higher frequency than light

  16. Which wave diffracts more through a 2 cm gap: sound of wavelength 2 m, or light of wavelength 600 nm?

    • they diffract equally
    • neither diffracts
    • the sound
    • the light

  17. If the line spacing of a grating decreases (d gets smaller), what happens to the angle of a given order?

    • It decreases
    • It is unchanged
    • It increases
    • It becomes zero

  18. In single-slit diffraction, at what condition does the first minimum occur?

    • a sin θ = λ/2
    • a sin θ = λ
    • a sin θ = 2λ
    • a sin θ = 0

  19. If the wavelength is doubled for a fixed grating and first order, what happens to sin θ?

    • It is unchanged
    • It doubles
    • It halves
    • It quadruples

  20. Why does white light passing through a grating form a spectrum?

    • Each wavelength diffracts through a different angle
    • Each colour has a different slit spacing
    • Light speeds up as it crosses the grating
    • The grating absorbs all colours except one

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