Question

A copper and a steel wire of the same diameter are connected end to end. A deforming force F is applied to this composite wire which causes a total elongation of 1 cm. The two wire will have

• A. The same stress
• B. Different stress
• C. The same strain
• D. Different strain

Answer 1

Answer: (A)

The same stress

$\text{Given,}$

$\begin{array}{c}\Delta \text{Lnet}=1cm\\ \text{we know,}\\ \begin{array}{c}y=\frac{F\cdot L}{A\cdot \Delta L}\\ \Delta L=\frac{FL}{AY}\end{array}\end{array}$

$\Delta L_1=\frac{FL}{A{Y}_{\text{steel}}},\Delta L_2=\frac{FL}{A{Y}_{\text{cupper}}}$

$\begin{array}{c}\text{So, strain will be different}\\ \therefore \text{stress}=\frac{F}{A}\\ \text{So, stress will be same for both wire}\end{array}$