Question

A copper wire and a steel wire of the same diameter and length are connected end to end and a force is applied, which stretches their combined length by 1 cm. The two wires will have

• A. Different stresses and strains
• B. The same stress and strain
• C. The same strain but different stresses
• D. The same stress but different strains

Answer 1

Answer: (D)

The same stress but different strains

Answer 2

Stress $= \frac { \text { Force } } { \text { area } }$.

In the present case, force applied and area of cross-section of wires are same, therefore stress has to be the same.

Strain $= \frac { \text { Stress } } { Y }$

Since the Young’s modulus of steel wire is greater than the copper wire, therefore, strain in case of steel wire is less than that in case of copper wire.