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

In Jager's method, at the time of bursting of the bubble

A cylinder with a movable piston contains air under a pressure $p_1$ and a soap bubble of radius $'r'$ . The pressure $p_2$ to which the air should be compressed by slowly pushing the piston into the cylinder for the soap bubble to reduce its size by half will be: (The surface tension is $\sigma $ , and the temperature $T$ is maintained constant)

If a section of soap bubble (of radius $R$) through its center is considered, then force on one half due to surface tension is

Two soap bubbles of radii ${r_1}$ and ${r_2}$ equal to $4 \,cm $ and $5 \,cm $ are touching each other over a common surface ${S_1}{S_2}$ (shown in figure). Its radius will be ....... $cm$

The diameter of rain-drop is $0.02 \,cm$. If surface tension of water be $72 \times {10^{ - 3}}\,newton$ per metre, then the pressure difference of external and internal surfaces of the drop will be