$A$ soap bubble is in the form of a circular tube having a radius of curvature $R$ and a radius of curvature perpendicular to it of $5R$. Find the excess pressure in the bubble.

What should be the diameter of a soap bubble,in order that the excess pressure inside it is $25.6 \ Nm^{-2}$ (in $cm$)? [surface tension of soap solution $= 3.2 \times 10^{-2} \ Nm^{-1}$]

Two small drops of liquid of same radius coalesce to form a big drop. The ratio of the total surface energies after and before the change is

When a big drop of water is formed from $n$ small drops of water, the energy loss is $3E$, where $E$ is the energy of the bigger drop. If $R$ is the radius of the bigger drop and $r$ is the radius of the smaller drop, then the number of smaller drops $(n)$ is:

$A$ big drop of radius $R$ is formed by $1000$ small droplets of water. The radius of each small droplet is:

Two soap bubbles with radii $r_1$ and $r_2$ $(r_1 > r_2)$ come in contact. Their common surface has a radius of curvature $r$. Find $r$.