Question

What is superficial expansion?​

Answer 1

The amount by which unit area of a material increases when the temperature is raised by one degree is called the coefficient of superficial (i.e. area) expansion and is represented by β (Greek beta).If a material having an initial surface area A1 at temperature t1 and having a coefficient of superficial expansion .

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Answer 2

Superficial Expansion

Superficial expansion is defined as the increase in surface area of the solid on heating.

Let $\sf{S}$ be the horizontal surface area of a solid and $\sf{\Delta S}$ be small increase in surface area of the solid, when it raised by small $\sf{\Delta T}$.

Then, it is found that,

$\sf{\implies \Delta S \propto S}$

$\sf{\implies \Delta S \propto \Delta T}$

Containing all these factors;

$\sf{\implies \Delta S \propto S \Delta T}$

$\sf{\implies \boxed{\sf{\;\Delta S = \beta S \Delta T\;}}}$

Where $\sf{\beta}$ is the coefficient of proportionality and is called the coefficient of superficial expansion.

Superficial expansion depends on the nature of the material amount of heat supplied and is measured in $\sf{^{\circ}C^{-1}}$ or $\sf{K^{-1}}$.