Q.A clean glass capillary tube of internal radius $0.20\ \text{mm}$ is dipped vertically into a beaker of water (surface tension $0.072\ \text{N/m}$, density $1000\ \text{kg/m}^3$), the water wetting the glass completely so that the angle of contact may be taken as $0°$. Calculate the height to which water rises in the capillary tube above the free surface in the beaker. (Take $g = 9.8\ \text{m/s}^2$.)

Given: $T = 0.072\ \text{N/m}$, $\rho = 1000\ \text{kg/m}^3$, $r = 0.20\ \text{mm} = 2.0\times10^{-4}\ \text{m}$, $\theta = 0°$ so $\cos\theta = 1$, $g = 9.8\ \text{m/s}^2$. …

Substitute the given surface tension, density, radius, and $\cos\theta = 1$ (since $\theta = 0°$ for water completely wetting cl …

• Forgetting to convert the radius from millimetres to metres, which changes the answer by a factor of $1000$. …