\(Y=\frac{F L}{A \Delta L} \Rightarrow \text { Percentage increase } \frac{\Delta L}{L} \times 100=\frac{F}{A Y} \times 100\)

\(\text { Diameter }=2.5 \,mm\)

\(d=\frac{2.5}{1000} \,m\)

Area \(=\frac{\pi d^2}{4} \quad Y=12.5 \times 10^{11} \,dyne / cm ^2\)  \(\left\{\frac{1 \text { dyne }}{ cm ^2}=\frac{0.1 \,N }{ m ^2}\right\}\)

\(\Rightarrow A=\frac{\pi \times(2.5)^2}{4} \quad F=100 \times 10=1000 \,N\)

\(\Rightarrow \frac{1000 \times L}{\frac{3.14 \times(2.5)^2}{4 \times(1000)^2} \times 12.5 \times 10^{11} \times 0.1}=\frac{\Delta L}{L} \times 100\)

\(=0.16 \%\)