$A$ thin liquid film formed between a $U$-shaped wire and a light slider supports a weight of $1.5 \times 10^{-2} \; N$ (see figure). The length of the slider is $30 \; cm$ and its weight is negligible. The surface tension of the liquid film is (in $; N m^{-1}$)

If the surface area of the soap solution is increased,then its surface tension

$n$ number of liquid drops each of radius $r$ coalesce to form a single drop of radius $R$. The energy released in the process is converted into the kinetic energy of the big drop so formed. The speed of the big drop is [$T = \text{surface tension of liquid}, \rho = \text{density of liquid}$.]

If the work done in increasing the size of a soap film from $10\, cm \times 6\, cm$ to $60\, cm \times 11\, cm$ is $2 \times 10^{-4}\, J$,what is the surface tension?

Why is the surface tension of antiseptics kept low? Explain.

$A$ disc of paper of radius $R$ has a hole of radius $r$. It is floating on a liquid of surface tension $T$. The force of surface tension on the disc is