Question

In a series combination of copper and steel wires of same length and same diameter, a force is applied at one of their ends while the other end is kept fixed. The combined length is increased by $2cm$. The wires will have

• A. Same stress and same strain
• B. Different stress and different strain
• C. Different stress and same strain
• D. Same stress and different strain

Answer 1

Answer: (D)

Stress $=\frac{F}{A}$
Force is same, $A$ is same
So same stress
Strain $=\frac{\Delta L}{L}$
$L$ is same, but due to different young's modulus (Material's different)
$\Delta L$ would be different so strain is different