If the diameter of a capillary is doubled, then the rise of water in it will be
(1) two times
(2) half
(3) four times
(4) no change
Answer: (2) Radius of a capillary tube is inversely proportional to the height of the liquid column. So, if the radius of the tube is doubled, the rise of the level of water will become half of the previous rise in a capillary tube. Capillary action, or capillarity, is the ability of a liquid to flow in narrow spaces without the assistance of, and in opposition to external forces like gravity. The effect can be seen in the drawing up of liquids between the hairs of a paint-brush, in a thin tube, in porous materials such as paper, in some non-porous materials such as liquefied carbon fibre, or in a cell. It occurs because of inter-molecular attractive forces between the liquid and solid surrounding surfaces.
