Practice question
Question
A copper wire of length 2.2m and cross-sectional area 1.8×10−6m2 is stretched by a force of 180N. If the Young's modulus of copper is 1.1×1011N/m2, what is the strain?
Explanation
Stress: Stress = FA = 1801.8×10−6 = 1×108N/m2. Young's modulus: Y = StressStrain. Strain: Strain = StressY = 1×1081.1×1011≈9.09×10−4. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 9.09×10−4. This satisfies dimensional consistency and physical conditions given, so option C is scientifically correct.