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A water drop of radius ' $r$ ' and volume ' $\mathrm{V}$ ' is kept in between the two identical glass plates such that it forms a thin layer of area ' $\mathrm{A}$ ' between the plates. A force ' $\mathrm{F}$ ' is applied such that the two plates separate from each other. The surface tension ' $\mathrm{T}$ ' of the liquid is
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Verified Answer
The correct answer is:
$\frac{F V}{2 A^2}$
Consider complete wetting.
The Laplace pressure jump is given by:
On plugging into equation (1), $\frac{\mathrm{T}}{\left(\frac{\mathrm{V}}{2 \mathrm{~A}}\right)}=\frac{\mathrm{F}}{\mathrm{A}}$
$$
\therefore \mathrm{T}=\frac{\mathrm{FV}}{2 \mathrm{~A}^2}
$$
The Laplace pressure jump is given by:
On plugging into equation (1), $\frac{\mathrm{T}}{\left(\frac{\mathrm{V}}{2 \mathrm{~A}}\right)}=\frac{\mathrm{F}}{\mathrm{A}}$
$$
\therefore \mathrm{T}=\frac{\mathrm{FV}}{2 \mathrm{~A}^2}
$$
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