If a soap bubble expands, the pressure inside the bubble:

The volume of an air bubble becomes three times as it rises from the bottom of a lake to its surface. Assuming atmospheric pressure to be $75\, cm$ of $Hg$ and the density of water to be $1/10  $ of the density of mercury, the depth of the lake is ....... $m$

The pressure inside a small air bubble of radius $0.1\, mm$ situated just below the surface of water will be equal to   [Take surface tension of water $70 \times {10^{ - 3}}N{m^{ - 1}}$ and atmospheric pressure = $1.013 \times {10^5}N{m^{ - 2}}$]

A bubble of $8$ mm diameter is formed in the air. The surface tension of soap solution is $30$ dynes/cm. The excess pressure inside the bubble is ........ $dynes/cm^2$

If two glass plates have water between them and are separated by very small distance ( see figure), it is very difficult to pull them apart. It is because the water in between forms cylindrical surface on the side that gives rise to lower pressure in the water in comparison to atmosphere. If the radius of the cylindrical surface is $R$ and surface tension of water is $T$ then the pressure in water between the plates is lower by

A drop of water volume $0.05\ cm^3$ is pressed between two glass-plates, as a consequence of which, it spreads between the plates. The area of contact with each plate is $40\ cm^2$ . If the surface tension of water is $70 \ dyne/cm$ , the minimum normal force required to seperate out the two glass plate in  newton is approximately...... $N$ (assuming angle of contact is zero)