Question

State coefficient of thermal expansion of a solid. What is its SI unit?
[4 marks]

Answer 1

Coefficients of thermal expansions of solids:
To measure and compare the amount of expansion of different solids along their lengths, surfaces and volumes we use three coefficients of thermal expansions. There are:
(1) Coefficient of linear expansion: The coefficient of linear expansion of a solid is the increase in its length per unit length per degree rise of temperature. It is denoted by $\alpha$. [1 mark]
(ii) Coefficient of surface expansions: The coefficient of surface expansion of a solid is the increase in the surface area per unit area per degree rise of temperature. It is normally denoted by $\beta$. [1 mark]
(iii) Coefficient of volume expansion: The coefficient of volume or cubical expansion of a solid is the increase in it's volume per unit volume per degree rise of temperature. It is usually denoted by $\gamma$. [1 mark]

The S.I. unit of coefficient of thermal expansion is per kelvin. $\left(K^{-1}\right)$​​​​​​[1 mark]