MCQ practice · SSC Physics Board questions · Chapter 1: Physical Quantities and Their Measurements
The cross-sectional area of the wire is−
Think it through first, then pick an option.
- a 3.77 mm²
- b 4.524 mm²
- c 9.048 mm²
- d 18.096 mm²
Answer and explanation
Correct answer: b 4.524 mm²
Diameter = 2 mm + 0.4 mm = 2.4 mm, radius = 1.2 mm; area = πr² = 3.14 × 1.2² ≈ 4.524 mm².
Why the other options are wrong
- a 3.77 mm²: 3.77 mm² is wrong; it is π × 1.2, found without squaring the radius.
- c 9.048 mm²: 9.048 mm² is wrong; it is twice the correct value; the area is πr² with r = 1.2 mm.
- d 18.096 mm²: 18.096 mm² is wrong; it takes the diameter 2.4 mm as the radius; the correct radius is 1.2 mm.
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