Question

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

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

Answer 1

The correct option is C $OA$


Here, $\Delta x_A>\Delta x_B>\Delta x_C>\Delta x_D$
For the same load, elongation in wire $OA$ is more than other wires.
We know, elongation $\Delta x=\frac{FL}{AY}$
But $F,L,Y$ are constant
So, $\Delta x\propto \frac{1}{A}$
$\therefore$ For the same load, wire with maximum elongation has minimum cross-section area.
So, here wire $OA$ has maximum elongation, therefore, thinnest wire is represented by line $OA$.