Question

A brass sheet is $25$ cm long and $8$ cm breadth at $0^{\circ }C$. Its area at ${100}^{\circ }C$ is $(\alpha =18\times {10}^{-6}{/}^{\circ }C)$ :

• A. $207.2c{m}^2$
• B. $200.72c{m}^2$
• C. $272c{m}^2$
• D. $2000.72c{m}^2$

Answer 1

Answer: (B)

$200.72c{m}^2$

$\alpha =18\times {10}^{-6}$ (Given)

$\beta =2\alpha$
So, $\beta =36\times {10}^{-6}$
Area $=$ $25\times 8$ $=$ 200 sq cm

$A_2=A_1(1+\beta \Delta T)$
So, final area $=$ $200(1+36\times {10}^{-6}\times 100)$ $=$ $200.72$ sq cm