Identical spring of steel and copper are equally stretched. On which, more work will have to be done ?

Explanation

Work done `W = (1)/(2) F xx Delta l or W prop Delta l ("for the given F")`
and ` Delta l = (F)/(A) xx (l)/(Y) or Delta l prop (1)/(Y) ("As F, A and l are constant")`
` :' W prop (1)/(Y)`
Hence, `(W_(steel))/(W_(copper)) = (Y_(copper))/(Y_(steel)) lt :. Y_(copper) lt Y_(steel)`
or `W_(steel) lt W_(copper)`
Hence more work will be done in case of copper spring.