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Topic Photoelectric effect
Asked 2 times across 2 UPSC exams over 5 years (2020–2025), peaking in 2020.
Key insights
- Most tested in CAPF — 1 of 2 PYQs
- Most asked in 2020
- Recurs across 2 years (2020–2025)
How it travelled across exams
First appearance in each exam — the same idea, reframed.
CAPF 2020 → GEO 2025
How the concept evolved
Rising — more than half its appearances (2 of 2) 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.
GEO2025
A threshold frequency for photoelectric emission in copper is 1.1×10¹⁵ Hz. When the light of frequency 1.2×10¹⁵ Hz is incident on the copper surface, the maximum energy of emitted particles would be (Planck's constant is 6.62×10⁻³⁴ J·s and the charge on the electron is 1.6×10⁻¹⁹ C)
- A 0.414 eV ✓
- B 4.14 eV
- C 41.4 eV
- D 0.828 eV
✓ Correct answer: (A)
Science & Technology › Physics & Chemistry
CAPF2020
Which one of the following statements on photoelectric effect is NOT correct?
- A Albert Einstein received the Nobel Prize in Physics for explaining photoelectric effect
- B For each metal, there is a threshold frequency, below which this effect is not observed
- C At a frequency v > v0, the kinetic energy of ejected electrons does not change on increasing the frequency of incident light ✓
- D The number of electrons ejected is proportional to the intensity of incident light
✓ Correct answer: (C)
Science & Technology › Physics & Chemistry
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