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Topic Wave motion
Asked 5 times across 3 UPSC exams over 9 years (2016–2025), peaking in 2025.
Key insights
- Most tested in CDS — 3 of 5 PYQs
- Most asked in 2025
- Recurs across 4 years (2016–2025)
How it travelled across exams
First appearance in each exam — the same idea, reframed.
CDS 2016 → CAPF 2019 → NDA 2025
How the concept evolved
Rising — more than half its appearances (5 of 5) are since 2016.
Related concepts
Ideas UPSC tests alongside this one — keep exploring.
Sample questions
You've seen the pattern — here are a few of the actual PYQs.
CDS2025
A sound wave travelling at a speed of 330 m/s produces 20 crests and 20 troughs in 0·1 second. The wavelength of the sound wave is :
- A 1·1 m
- B 3·3 m
- C 1·65 m
- D 2·2 m
Answer key not yet available (pending official release)
Science & Technology › Physics & Chemistry
NDA2025
The frequency (f), wavelength (λ) and speed (v) of a sound wave are related as
- A f = vλ
- B λ = vf
- C f = λ/v
- D v = λf ✓
✓ Correct answer: (D)
Science & Technology › Physics & Chemistry
CDS2024
A sound wave having frequency of 300 Hz is travelling in an unknown medium. Its wavelength is not known. It travels a distance equal to 150 times its wavelength in time t. The value of t is :
- A 0·5 s ✓
- B 1 s
- C 1·5 s
- D 2 s
✓ Correct answer: (A)
Science & Technology › Physics & Chemistry
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