Physics - Fluid Question with Solution | TestHub

Let $t$ be the thickness of the liquid layer between the two glass plates.

The volume of the liquid is given by $V=At\Rightarrow t=\frac{V}{A}$.

The radius of curvature of the meniscus formed at the edge of the liquid layer is $r=\frac{t}{2}$.

The pressure difference across the free surface of the liquid is $\Delta P=\frac{T}{r}=\frac{2T}{t}$, where $T$ is the surface tension.

The force required to separate the two glass plates is $F=\Delta P\times A$.

Substituting the value of $\Delta P$, we get $F=\frac{2TA}{t}$.

Substituting $t=\frac{V}{A}$, we get $F=\frac{2T{A}^2}{V}$.

Rearranging for surface tension $T$, we get $T=\frac{FV}{2A^2}$.

Answer: $\frac{FV}{2A^2}$