# Two wires A and B of equal cross sectional area are in series,stretches equally is $Y_A=3\times 10^{11}$ and $Y_B=1.8\times 10^{11}$.What is ratio of their length?

$\begin{array}{1 1}(A)\;1 : 1\\(B)\;3 : 1.8\\(C)\;1.8 : 3\\(D)\;3.24 : 9\end{array}$

In series force is same
$Y \propto l$
So $\large\frac{l_A}{l_B}=\frac{Y_A}{Y_B}=\frac{3}{1.8}$
Hence ratio of their length is 3 : 1.8
Hence (B) is the correct answer.