Practice question
Question
A steel wire of length 2.8m and cross-sectional area 3×10−6m2 is stretched by 0.7mm. If the Young's modulus of steel is 2×1011N/m2, what is the strain?
Explanation
Strain: Strain = ΔLL = 0.7×10−32.8 = 2.5×10−4. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 2.5×10−4. This satisfies dimensional consistency and physical conditions given, so option D is scientifically correct.