Problem 2.179

Find the free energy of the surface layer of (a) a mercury droplet of diameter $d=1.4 \mathrm{~mm}$ (b) a soap bubble of diameter $d=6.0 \mathrm{~mm}$ if the surface tension of the soap water solution is equal to $\alpha=45 \mathrm{mN} / \mathrm{m}$ .

\text { (a) } F=\pi \alpha d^{2}=3 \mu \mathrm{J} \text { (b) } F=2 \pi \alpha d^{2}=10 \mu \mathrm{J} \text { . }

Liquids. Capillary effects