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Topic Thermal expansion
Asked 4 times across 3 UPSC exams over 42 years (1979–2021), peaking in 1979.
Key insights
- Most tested in CDS — 2 of 4 PYQs
- Most asked in 1979
- Recurs across 4 years (1979–2021)
How it travelled across exams
First appearance in each exam — the same idea, reframed.
CSE 1979 → CDS 2014 → GEO 2021
How the concept evolved
Long-running — most appearances (3 of 4) predate 2016, and it still returns.
Sample questions
You've seen the pattern — here are a few of the actual PYQs.
GEO2021
A copper rod of length 1 m is initially at room temperature. If the temperature of the rod is increased by 100 °C, what will be the change in length of the rod? (Given linear thermal expansion coefficient of Cu is 17 x 10⁻⁶/°C)
- A 0.17 mm
- B 1.7 mm
- C 0.17 cm
- D 1.7 cm
Answer key not yet available (pending official release)
Science & Technology › Physics & Chemistry
CDS2015
A metallic plate sticks firmly on the mouth of a water filled vessel made from another metal. By way of heating, one can detach the plate from the vessel. This is because heat expands
- A the vessel only
- B both the vessel and the plate equally
- C the vessel more than the plate ✓
- D the vessel and contracts the plate
✓ Correct answer: (C)
Science & Technology › Physics & Chemistry
CDS2014
A metal screw-top on a glass bottle which appears to be stuck could be opened by using the fact that
- A the metal expands more than the glass when both are heated ✓
- B the metal and glass expand identically when heated
- C the metal shrinks when heated
- D both metal and glass shrink when cooled
✓ Correct answer: (A)
Science & Technology › Physics & Chemistry
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