With an illustration, explain the method of calculation for areal expansion of an object.

Explanation

(i) If there is an increase in the area of a solid object due to heating, then the expansion is called superficial or areal expansion.
(ii) Superficial expansion is determined in terms if coefficient of superficial expansion.
(iii) The ratio of increase in area of the body per degree rise in temperature to its unit area is called coefficient of superficial expansion is different for different materials.
(iv) SI unit is also `K^(-1)`.
(v) The equation relating to the change in area to the change in temperature is given below:

`(DeltaA)/(A_(0)) = alpha_(A) DeltaT`
`DeltaA` -Change in area
`A_(0)` - Original area
`DeltaT` -Change in temperature
`alpha_(A)` - Coefficient of superficial expansion.