Question

A crystal has a coefficient .Of expansion $13\times {10}^{-7}$ in one direction and $231\times {10}^{-7}$ in every direction at right angles to it. Then the cubical coefficient of expansion is

• A. $462\times {10}^{-7}$
• B. $244\times {10}^{-7}$
• C. $475\times {10}^{-7}$
• D. $257\times {10}^{-7}$

Answer 1

Answer: (C)

$475\times {10}^{-7}$

The cubical expansion is defined as the sum three linear coefficients in three perpendicular directions

$\gamma ={\alpha }_1+{\alpha }_2+{\alpha }_3$

$\Rightarrow 13\times {10}^{-7}+231\times {10}^{-7}+231\times -7$

$\gamma =475\times {10}^{-7}{/}^{o}C$