Define capillary tube?

A capillary tube is a very thin tube used to study the flow of liquids in narrow spaces. It has a very small internal diameter and is often made of glass. Capillary tubes are used in science labs and medical devices. When placed in a liquid, the liquid can rise or fall inside the tube due to surface tension. This is called capillary action.

Examples of capillary action:

• Water rising in a thin glass tube
• Ink flowing in blotting paper
• Water moving in plant roots and stems

Capillary tubes help scientists study the behavior of fluids and are used in thermometers and refrigeration systems.