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Physical optics test with answers for AP Physics 2 (free PDF download)

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Quick answer: Physical optics explains light and sound as waves that add together. This AP Physics 2 test on physical optics has 8 questions worth 20 marks, to do in 40 minutes: double slit calculation, changing the set-up and oil film. The mark scheme is on a separate page; free printable PDF.

Physical optics test with answers for AP Physics 2 (free PDF download)

This AP Physics 2 test on physical optics test works like a real class test. The mark scheme is on a separate page, so revise with the lesson first.

This test checks calculations with interference, standing waves and the Doppler effect together with short explanations. Give every answer with its unit. Show every step for full credit.

Level: AP Physics 2 (algebra-based) · Curriculum: AP P2 Unit 14

Physical optics test: the test questions

Time: 40 minutes · 8 questions · Total: 20 marks · Calculator allowed

Question 1 Double slit calculation (3 marks)

A laser of wavelength 520 nm lights two slits 0.15 mm apart. The screen is 1.80 m away.
  1. Calculate the spacing between neighbouring bright fringes. (2 marks)
  2. Calculate the distance from the centre to the third bright fringe. (1 mark)

Question 2 Changing the set-up (2 marks)

The slit spacing is halved and the screen is moved to half the distance. All other conditions stay the same.
  1. Predict the new fringe spacing in terms of the old one. (1 mark)
  2. Explain your reasoning. (1 mark)

Question 3 Oil film (3 marks)

A thin film of oil (n = 1.45) floats on water (n = 1.33). Light of wavelength 580 nm in air strikes it at normal incidence.
  1. State which reflection flips the phase. (1 mark)
  2. Calculate the minimum thickness for strong reflection. (2 marks)

Question 4 Standing wave on a string (2 marks)

The figure shows a standing wave on a string fixed at both ends.
A string fixed at both ends showing a standing wave with three loops, length 1.2 metresL = 1.2 m
A standing wave on a string with three loops.
The wave speed on the string is 48 m/s.
  1. Calculate the wavelength. (1 mark)
  2. Calculate the frequency. (1 mark)

Question 5 Closed pipe (3 marks)

A pipe of length 0.85 m is closed at one end. Sound speed is 340 m/s.
  1. Calculate the fundamental frequency. (1 mark)
  2. Calculate the frequency of the next resonance. (1 mark)
  3. Explain why no resonance occurs at twice the fundamental. (1 mark)

Question 6 Moving source (3 marks)

A source of frequency 800 Hz moves toward a listener at 20 m/s. Sound speed is 340 m/s.
  1. Calculate the frequency heard as it approaches. (1 mark)
  2. Calculate the frequency heard as it recedes. (1 mark)
  3. Explain why the frequency changes. (1 mark)

Question 7 White-light fringes (2 marks)

White light is passed through a double slit.
  1. State the colour of the central fringe. (1 mark)
  2. Explain why coloured edges appear on the other fringes. (1 mark)

Question 8 Beats (2 marks)

Two notes of frequency 512 Hz and 516 Hz sound together.
  1. Calculate the beat frequency. (1 mark)
  2. Calculate the time between loud sounds. (1 mark)

See the physical optics test answers and mark scheme

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