Question

If the surface tension of a liquid is T and its surface are is increased by A, then the surface energy of that surface will be increased by :-

• A. AT
• B. $\frac{A}{T}$
• C. $A^{2}T$
• D. $A^2{T}^2$

Answer 1

The correct option is A AT

The surface energy of a fluid is defined as the product of the surface tension of the fluid and the area on which it is acting.

Therefore, the change in energy is equal to the surface tension times the change in area.

Therefore, $\delta U=T\times \delta A$

= TA

We can also arrive at the same result by looking at the dimensions.

[T] = $M{T}^{-2}$

[A] = $l^2$

[AT] = $M{L}^2{T}^{-2}$

Dimensions of energy, = FL = $ML{T}^{-2}L$

E = $M{L}^2{T}^{-2}$