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 $1cm$. The two wires will have

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

Answer 1

The correct option is C the same stress but different strains

As we know,

$\text{stress}=\frac{force}{area}$

As given in question, both wires have same force and same cross-sectional area. Therefore, stress is same for both copper and steel wire.

Then,
Young modulus of steel wire is more than a copper wire. Therefore, strain is different for both wires as,

$\text{strain}=\frac{stress}{Y}$

Hence, both copper and steel wire have same stress but different strain.