Question

Choose the correct options from the following.

• A. Bimetallic strip bends when we heat it.
• B. The coefficient of linear expansion does not depend upon temperature.
• C. Coefficient of surface expansion's unit is ${}^{\circ }{C}^{-1}$.
• D. None of these

Answer 1

Answer: (A), (C)

The correct options are
A

Bimetallic strip bends when we heat it.

C

Coefficient of surface expansion's unit is ${}^{\circ }{C}^{-1}$.

(A) Bimetallic strip bends because different metals expand differently.
(B) $\alpha$ = Coefficient of linear expansion is the increase in the length of an object per unit length per degree rise in temperature.

Let $l_1$ and $l_2$ be the length of a solid at $t_1$ and $t_2$ temperatures respectively.
Then $\alpha =\frac{l_2-l_1}{l_1(t_2-t_1)}$, $\alpha =coefficientoflinearexpansion$
Since, It is the ratio of length. Its unit does not depend on length.It only depends on the temperature.

(C) Coefficient of surface expansion $\left(\beta \right)$ is ${}^{\circ }{C}^{-1}$.