Question

Explain the rise of liquid in the capillary on the basis of pressure difference.

Answer 1

Hint: A capillary tube is a simple cylindrical object with no moving parts in it. The capillary tube is generally made up of copper or glass. There are various applications of the capillary tube such as it is used in refrigerators in regulating the flow of refrigerant in the tube.

Complete solution:
Suppose we dip a capillary tube in water. The water will form a curved upper surface with the tube called meniscus which is due to the angle made by the water with the tube at the time of contact. The curvature of the curved upper surface (meniscus) will be greater as the width of the tube gets narrower. The happening of the curvature causes a pressure difference to develop across the liquid gas interface.
A liquid with contact angle less than 90 degrees will form a concave meniscus and the liquid pressure under the meniscus $(P_1)$ will be smaller than the atmospheric pressure. As a result, the water inside the tube will be forced upwards in the tube from its initial location by great pressure of the water outside the tube at the same level. The movement of the water which is upward will stop when the pressure difference between the water inside the tube and outside would be equal.

Note: Here, explain the capillary tube and its action known as capillary action with the help of a diagram. Explain about the process that is happening inside and outside the tube.