Three liquids of densities $\rho_1, \rho_2$ and $\rho_3$ (with $\rho_1\rho_2\rho_3$ ), having the

Question

Three liquids of densities $ho_1, ho_2$ and $ho_3$ (with $ho_1>ho_2>ho_3$ ), having the same value of surface tension $T$, rise to the same height in three identical capillaries. The angles of contact $	heta_1, 	heta_2$ and $	heta_3$ obey

Professor PC Thomas Classes · Answer

Capillary rise $h = \frac{2T \cos heta}{ ho g r}$. Since $h, T, r$ are same, $ ho \propto \cos heta$. As $ ho_1 > ho_2 > ho_3$, $\cos heta_1 > \cos heta_2 > \cos heta_3 \implies heta_1 < heta_2 < heta_3 < \frac{\pi}{2}$.