Practise 50 real questions on Waves from 2021 to 2026. See the answer and explanation as soon as you answer.
Waves is one of the 13 main topics in our A Level Physics (Cambridge (CAIE) 9702) question bank, and about 7% of its real questions come from it. Tayyari Karo has 50 real questions on this topic from 2021 to 2026, from Paper 1, Paper 2; 47 are multiple choice and marked instantly, and the rest are structured questions with a model answer. By difficulty: 24 medium, 14 hard, 12 easy.
Work through the questions below, then open the explanation for each one. Redo the ones you missed a few days later.
These are real past-paper questions. Think of your answer first, then open the explanation.
A vertically polarised electromagnetic wave has an intensity of 3.2 × 10⁴ W m⁻². The wave is incident on a polarising filter that has a transmission axis at an angle θ to the vertical. The transmitted wave has an intensity of 2.5 × 10⁴ W m⁻².
What is θ?
Answer: A. 28°
I = I₀cos²θ, so cos²θ = 2.5/3.2 = 0.78, cosθ = 0.884 and θ = 28°.
Which wavelength of electromagnetic radiation in free space could be green light?
Answer: C. 5.5×10⁻⁷ m
Visible light has wavelengths roughly 400–700 nm (4–7×10⁻⁷ m); green light is near 550 nm = 5.5×10⁻⁷ m.
An electromagnetic wave is travelling through a vacuum. What could be the wavelength and period of the electromagnetic wave?
A: wavelength 1.2×10⁻¹⁰ Tm, period 2.5 Ms
B: wavelength 1.2 pm, period 2.5×10¹¹ Gs
C: wavelength 1.2×10² pm, period 4.0×10⁻¹⁰ ns
D: wavelength 1.2×10³ m, period 4.0 ns
Answer: C. 1.2×10² pm and 4.0×10⁻¹⁰ ns
For an EM wave in vacuum, c = λ/T. Option C: λ = 1.2×10² pm = 1.2×10⁻¹⁰ m; T = 4.0×10⁻¹⁰ ns = 4.0×10⁻¹⁹ s; λ/T = 1.2×10⁻¹⁰/4.0×10⁻¹⁹ = 3.0×10⁸ m s⁻¹ = c. The other options do not give c when λ is divided by T.
Four sources of electromagnetic waves in free space are listed: 1 a radio wave transmitter; 2 a source of X-rays; 3 a 30 mm wavelength radar transmitter; 4 a light-emitting diode that emits red light. Which list gives the sources in order of increasing wavelength, from left to right, of the waves emitted?
Answer: C. 2 4 3 1
Increasing wavelength: X-rays (shortest) < red light (~700 nm) < 30 mm radar < radio waves (longest), i.e. order 2, 4, 3, 1.
A signal generator, amplifier and loudspeaker are used to produce different sound waves in a room. Which relationship is not correct?
Answer: A. Amplitude is proportional to wavelength.
Amplitude and wavelength are independent properties of a wave; there is no proportionality between them.
Microwaves in a vacuum travel at speed X and have wavelength of order of magnitude Y. What are the speed and a possible order of magnitude of wavelength of X-rays in a vacuum?
Answer: A. speed X, wavelength 10⁻⁸Y
All electromagnetic waves travel at the same speed c in a vacuum, so the speed is still X. X-rays have wavelengths roughly 8 orders of magnitude shorter than microwaves, so wavelength ≈ 10⁻⁸Y.
| Session | Paper 1 | Paper 2 |
|---|---|---|
| May/June 2026 | 4 | – |
| May/June 2025 | 5 | 1 |
| October/November 2025 | 4 | – |
| May/June 2024 | 6 | – |
| October/November 2024 | 3 | – |
| May/June 2023 | 3 | – |
| October/November 2023 | 3 | 1 |
| May/June 2022 | 5 | – |
| October/November 2022 | 4 | – |
| May/June 2021 | 5 | – |
| October/November 2021 | 5 | 1 |
50 real A Level Physics (9702) questions on Waves from 2021 to 2026, from Paper 1, Paper 2. Each one shows the year, session and paper it came from.
Yes. Every question shows the correct answer and a short explanation the moment you answer.
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