c
(c) Work done in stretching a wire
$W = \frac{1}{2}Fl = \frac{1}{2} \times 10 \times 0.5 \times {10^{ - 3}}$= $2.5 \times {10^{ - 3}}J$
Work done to displace it through $1.5 \,mm$
$W = F \times l = 5 \times {10^{ - 3}}J$
The ratio of above two work $= 1 : 2$