Practice question
Question
A silver rod of length 1m at 10∘C is heated to 110∘C. If its cross-sectional area increases by 0.0076cm2, what was its original area? (αl\=1.9×10−5K−1)
Explanation
Given: ΔT = 110−10 = 100∘C, ΔA = 0.0076cm2, αl = 1.9×10−5K−1. ΔA = A0×2αlΔT. 0.0076 = A0×2×1.9×10−5×100. 0.0076 = A0×3.8×10−3⇒A0 = 0.00763.8×10−3 = 2cm2. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 2 cm². This satisfies dimensional consistency and physical conditions given, so option D is scientifically correct.
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