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Topic Refraction
Asked 32 times across 5 UPSC exams over 37 years (1988–2025), peaking in 2021.
Key insights
- Most tested in CDS — 12 of 32 PYQs
- Most asked in 2021
- Recurs across 12 years (1988–2025)
How it travelled across exams
First appearance in each exam — the same idea, reframed.
CSE 1988 → CDS 2014 → CAPF 2017 → NDA 2020 → GEO 2021
How the concept evolved
188
191
113
214
116
117
320
1121
322
323
324
225
Rising — more than half its appearances (27 of 32) 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
Twinkling of a star is due to :
- A Interference of light
- B Refraction of light
- C Polarization of light
- D Diffraction of light
Answer key not yet available (pending official release)
Science & Technology › Physics & Chemistry
GEO2025
A glass bar (refractive index = 1·5) is immersed in a liquid having the same refractive index as that of glass. The angle of incidence for a light ray at which the light would be transmitted through the glass bar without reflecting is
- A 30°
- B 45° ✓
- C 60°
- D 75°
✓ Correct answer: (B)
Science & Technology › Physics & Chemistry
CDS2024
The phenomenon of rainbow formation by water droplets involves :
- A single refraction of sunlight
- B one internal reflection of sunlight
- C two internal reflections of sunlight
- D both refraction and internal reflection of sunlight ✓
✓ Correct answer: (D)
Science & Technology › Physics & Chemistry
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