Question

The property due to which the free surface of liquid tends to have minimum surface area and behaves like a stretched membrane is called surface tension. It is a force per unit length acting in the plane of interface between the liquid and the bounding surface i.e., S = F/L, where F = force acting on either side of imaginary line on surface and L = length of imaginary line. Surface tension decreases with rise in temperature. Highly soluble impurities increases surface tension and sparingly soluble impurities decreases surface tension.

A wooden stick 2m long is floating on the surface of water. The surface tension of water 0.07 N/m. By putting soap solution on one side of the sticks the surface tension is reduced to 0.06 N/m. The net force on the stick will be

The surface tension and vapour pressure of water at 20°C is 7.28 × 10⁻² N/m and 2.33 × 10³ Pa, respectively. What is the radius of the smallest spherical water droplet which can form without evaporating at 20°C?

Prove that excess pressure inside a soap bubble is inversely proportional to radius of bubble.