Two glass plates are separated by water. If surface tension of...

The shape of water layer between the two plates is shown in the figure. Thickness $d$ of the film $=0.12 \mathrm{~mm}$ $=0.012 \mathrm{~cm}$ Radius $R$ of the cylindrical face $=\frac{d}{2}$ Pressure difference across the surface $=\frac{T}{R}=\frac{2 T}{d}$ Area of each plate wetted by water $=A$ Force $F$ required to separate the two plates is given by $F=$ pressure difference $\times$ area $=\frac{2 T}{d} A$ Putting the given values, we get $F=\frac{2 \times 75 \times 8}{0.012}=10^5$ dyne