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 gets increased by $2\text{cm}$. 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

The correct option is D Same stress and different strain

Stress $=\frac{F}{A}$
Force$\left(F\right)$ is same, $A$ is same.
So stress will be same.
Strain $=\frac{\Delta L}{L}$
$L$ is same, but due to different young's modulus, $\Delta L$ would be different for copper and steel wire so strain is different .
$\because \text{Stress}=Y\times \text{Strain}$