# A tension of $20 \;N$ is applied to a copper wire of cross sectional area $0.01\;cm^2$, Young's Modulus of copper is $1.1 \times 10^{11} \;N/m^2$ and Poisson's ratio is $0.32$. The decrease in cross sectional area of the wire is

$(a)\;1.16 \times 10^{-6}\;cm^2 \quad (b)\;1.16 \times 10^{-5}\;m^2 \quad (c)\;1.16 \times 10^{-4}\;m^2 \quad (d)\;1.16 \times 10^{-3}\;cm^2$

$(a)\;1.16 \times 10^{-6}\;cm^2$