Question

The load versus elongation graph for four wires made of the same material and having the same length is shown in the figure. The thickest wire is represented by the line

• A. $OD$
• B. $OC$
• C. $OB$
• D. $OA$

Answer 1

The correct option is A $OD$

Elongation of a wire is $\Delta l=\frac{FL}{AY}$
Slope of $F$ vs $\Delta l$ graph is given by
$\frac{F}{\Delta l}=\frac{AY}{L}$
As $Y$ and $L$ are the same for wires of the same material and length,
Slope $\propto A$ (area of cross-section)
i.e Slope is highest for the thickest wire. Hence, from the graph, we can say that $OD$ is the thickest wire.
i.e option (a) is correct.