Which one of the following is not a result of surface tension ?
Nearly spherical drop of rain
Capillary rise
Removal of dirt by soap or detergent
Flow of a liquid
Answer is Right!
Answer is Wrong!
This question was previously asked in
UPSC NDA-1 – 2015
A) Nearly spherical drop of rain: Surface tension minimizes the surface area of the liquid, and a sphere has the minimum surface area for a given volume. This is a direct result of surface tension.
B) Capillary rise: This phenomenon, where a liquid rises in a narrow tube, is caused by the combined effects of surface tension and adhesion between the liquid and the tube walls. Surface tension contributes to the upward force.
C) Removal of dirt by soap or detergent: Soaps reduce the surface tension of water. This reduced surface tension allows the water to wet fabrics and dirt particles more effectively, helping in their removal. While it involves the *change* in surface tension, the ability to remove dirt in this way is linked to the surface properties facilitated by the detergent’s effect on surface tension.
D) Flow of a liquid: The bulk flow of a liquid (like water flowing in a pipe or a river) is driven by pressure differences or gravity, and it is resisted by viscosity. Surface tension primarily affects the liquid-air interface and phenomena occurring there (like drop formation, ripples), but it is not the fundamental cause or main characteristic of the bulk flow itself.