# Work done in increasing the length of $1\;m$ long wire of cross-sectional area $1\;mm^2$ through $1\;mm$ is $y=2 \times 10^{11}N/m^2$
$\begin {array} {1 1} (a)\;250\;J \\ (b)\;10\;J \\ (c)\;5\;J \\ (d)\;0.1\;J \end {array}$