The radius of a soap bubble is $r$, and the surface tension of the soap solution is $T$. Without increasing the temperature, how much energy is required to double its radius (in $\pi r^2 T$)?

Energy needed in breaking a liquid drop of radius $R$ into $n$ smaller drops,each of radius $r$,is [where $T$ is the surface tension of the liquid].

Surface tension of a soap solution is $1.9 \times 10^{-2} \text{ N/m}$. The work done in blowing a soap bubble of $2.0 \text{ cm}$ diameter will be:

What is the ratio of the surface energy of $1$ small drop to $1$ large drop,if $1000$ small drops combine to form $1$ large drop?

$A$ film of soap solution is formed between two straight parallel wires of length $10 \,cm$ each, separated by $0.5 \,cm$. If their separation is increased by $1 \,mm$ while still maintaining their parallelism, how much work will have to be done? (Surface tension of solution $= 65 \times 10^{-3} \,N/m$)

$A$ liquid film is formed in a loop of area $0.05 \, m^2$. The increase in its potential energy will be $(T = 0.2 \, N/m)$.