# Two rods of equal length are in parallel with area in the ratio 3 : 4 and young modulus in the ratio 5 : 3.The ratio of force on the rods is

$\begin{array}{1 1}(A)\;5 : 4\\(B)\;20 : 9\\(C)\;9 : 20\\(D)\;4 : 5\end{array}$

In parallel the extension is same so
$\Delta l_1=\Delta l_2$
$(\large\frac{F_1}{a_1})\frac{l}{Y_1}=(\large\frac{F_2}{a_2})\frac{l}{Y_2}$
$\large\frac{F_1}{F_2}=\frac{a_1Y_1}{a_2Y_2}$
$\Rightarrow \large\frac{3}{4}\times \frac{5}{3}$
$\Rightarrow \large\frac{5}{4}$
Hence (A) is the correct answer.