AS Level Physics chapter 8: Superposition MCQs with answers

By Team Megalecture · Updated 4 Nov 2026

90 exam-style questions on Superposition, each with the answer and a short explanation. Ten of them are below to try. The chapter test draws ten fresh questions each time and is marked the moment you finish, with your score by topic.

90 questions · 4 topics · 10 per test

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What chapter 8 covers

Ten Superposition questions with answers

Try each one, then open the answer. These ten stay the same; the test draws new ones every time.

1. Two coherent waves with amplitudes 3A and A interfere. What is the ratio of the intensity at a maximum to the intensity at a minimum?

  1. A
    2
  2. B
    4
  3. C
    9
  4. D
    16
Show answer

Answer: B. Maximum amplitude = 4A and minimum amplitude = 2A. Intensity ∝ amplitude2, so the ratio is (4/2)2 = 4. The amplitude ratio alone is 2.

2. Light from a laser passes through a single narrow slit onto a distant screen. The central bright band on the screen is much wider than the slit. Which effect causes this?

  1. A
    diffraction
  2. B
    dispersion
  3. C
    polarisation
  4. D
    refraction
Show answer

Answer: A. The light spreads out as it passes through the narrow gap: this is diffraction.

3. Point P on a stationary wave is λ/8 to the left of a node and point Q is λ/8 to the right of the same node. What is the phase difference between the oscillations of P and Q?

  1. A
    0°
  2. B
    45°
  3. C
    90°
  4. D
    180°
Show answer

Answer: D. Points in adjacent loops (on opposite sides of a node) oscillate in antiphase: 180°. 90° is the answer for a progressive wave over a distance of λ/4.

4. Using the same grating (d = 2.0 × 10−6 m) and 500 nm light, what is the highest order of maximum that can be observed?

  1. A
    2
  2. B
    3
  3. C
    4
  4. D
    5
Show answer

Answer: C. nmax = d/λ = 2.0 × 10−6 ÷ 5.0 × 10−7 = 4 (sin θ cannot exceed 1).

5. What is meant by interference?

  1. A
    the spreading of waves through a gap
  2. B
    the superposition of coherent waves to give regions of larger and smaller amplitude
  3. C
    the reflection of a wave back along its own path
  4. D
    the bending of waves at a boundary
Show answer

Answer: B. Interference is the superposition of two or more coherent waves, giving a fixed pattern of maxima and minima. Spreading through a gap is diffraction.

6. A tube of length 0.60 m is closed at one end and open at the other. Which wavelength of sound will NOT produce resonance in it? (ignore end corrections)

  1. A
    0.48 m
  2. B
    0.80 m
  3. C
    1.2 m
  4. D
    2.4 m
Show answer

Answer: C. A closed tube has a node at the closed end and an antinode at the open end, so L = λ/4, 3λ/4, 5λ/4..., giving λ = 2.4 m, 0.80 m, 0.48 m. λ = 1.2 m (L = λ/2) needs both ends open.

7. Why is a diffraction grating better than a double slit for measuring the wavelength of light?

  1. A
    it gives sharp, bright maxima at large angles, which can be measured precisely
  2. B
    it needs no light source
  3. C
    it produces more closely spaced fringes
  4. D
    it works only with white light
Show answer

Answer: A. Many slits make the maxima much sharper and brighter, and the angles are large, so the percentage uncertainty in θ is small.

8. In a ripple tank the waves travel at 0.15 m s−1. They pass through a gap 3.0 cm wide. At which frequency of the dipper is the spreading of the waves beyond the gap greatest?

  1. A
    5 Hz
  2. B
    10 Hz
  3. C
    20 Hz
  4. D
    40 Hz
Show answer

Answer: A. λ = v/f gives 3.0 cm, 1.5 cm, 0.75 cm and 0.375 cm. The spreading is greatest when the wavelength is closest to the gap width, at 5 Hz.

9. Two sinusoidal waves of the same frequency, with amplitudes 5.0 mm and 3.0 mm, meet at a point. The phase difference between them can have any constant value. Which resultant amplitude is impossible?

  1. A
    2.0 mm
  2. B
    5.0 mm
  3. C
    8.0 mm
  4. D
    9.0 mm
Show answer

Answer: D. The resultant amplitude lies between 5.0 − 3.0 = 2.0 mm (antiphase) and 5.0 + 3.0 = 8.0 mm (in phase). 9.0 mm is larger than the maximum, so it is impossible.

10. A double-slit experiment is carried out with white light. The central fringe is white, but the other bright fringes are coloured. Why?

  1. A
    the central fringe is brightest, so its colours merge
  2. B
    the slits absorb coloured light near the centre
  3. C
    white light is coherent only at the centre of the pattern
  4. D
    at the centre the path difference is zero for every wavelength, so all colours interfere constructively there
Show answer

Answer: D. Fringe spacing depends on wavelength, so away from the centre the maxima for different colours fall in different places. At the centre every wavelength has zero path difference.

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Ways to practise this chapter

Superposition: questions students ask

How many Superposition MCQs are there?

90, each with the answer and a short explanation, across 4 topics: Stationary waves, Diffraction, Interference, The diffraction grating. Every chapter test draws ten of them, so you can take it many times.

Is the AS Level Physics chapter 8 test free?

Yes. The test, the answers and the explanations are free and need no sign-up. Sign in only if you want your scores kept across devices.

How is the chapter test marked?

The moment you press Finish: your score, the right answer and an explanation for every question, and the ones you got wrong saved in My mistakes to retry.

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