Chapter 1, Problem 1.30P

Interpretation Introduction

Interpretation:

The glass tube diameter required to keep the change in the capillary height of water less than 1 mm at ${30}^{\circ }\text{C}$ is to be determined.

Concept Introduction:

For water, the intermolecular forces present between the molecules of liquid at the surface is less than the forces of attraction present between liquid water and the glass surface. This leads to the rise in the height of the liquid in the tube.

The formula used to calculate this height ( h ) is:

  $h=\frac{2\sigma \cos \theta }{\rho gr}$ ........(1)

Here, $\sigma$ is the surface tension, $\theta$ is the contact angle, $\rho$ is the density of the liquid, g is the acceleration due to gravity, and r is the radius of the tube.