Question

Two wires A and B of same length are made of same material. The figure represents the load F versus extension $\Delta x$ graph for the two wires. Then :

• A. the cross sectional area of A is greater than that of B.
• B. the elasticity of B is greater than that of A.
• C. the cross-sectional area of B is greater than that of A.
• D. the elasticity of A is greater than that of B.

Answer 1

The correct option is C the cross-sectional area of B is greater than that of A.

We have
$\Delta x=\frac{Fl}{AY}$
$F=\left(\frac{AY}{l}\right)\Delta x$
So, $F$ vs $\Delta x$ graphs are straight lines with slope $\frac{AY}{l}$, in which $Y$ and $l$ are constant.
So, the line with more slope has higher value of $A$.
From the figure, B has more slope, implies cross sectional area of B is higher.
Option C.