OPSC OAS 2023 PrelimsScience & TechnologyQuestion 1
Solved previous year question from the OPSC OAS/OCS 2023 Preliminary Examination (General Studies), with the official answer key and a detailed explanation.
Question
A square shaped hole is punched in a metal sheet whose linear thermal expansion coefficient is 1 × 10-3 per °C. The size of the hole will decrease by 10%, when
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Answer & Explanation
Correct answer: (C) The sheet is cooled by 100 °C
- Key principle: When a metal sheet with a hole is heated, the hole expands (gets larger) — just as if the hole were filled with the same material. Conversely, when cooled, the hole contracts (gets smaller).
- So to decrease the size of the hole, the sheet must be cooled.
| Action | Effect on hole |
|---|---|
| Heating | Hole expands — size increases |
| Cooling | Hole contracts — size decreases |
