Liquid becomes convex upward in capillary tube - Fluid Mechanics

Q.  When the angle between surface tension with the liquid (θ) is greater than 90o, the liquid becomes
- Published on 04 Aug 15

a. flat
b. concave upward
c. convex upward
d. unpredictable

ANSWER: convex upward


  • Pankaj   -Posted on 25 Sep 15
    The liquid level in the tube either falls or rises according to the liquid level in the pool, when a small diameter tube is inserted vertically inside a liquid pool. This phenomenon of rise or fall of liquid level in the capillary tube is called as capillarity.
    The liquid in the pool cannot wet the capillary tube if the cohesive force between molecules of liquid is more than the adhesive force between liquid molecules and glass tube. In this case the angle of surface tension with the vertical is greater than 90o and liquid becomes convex upward.
    The liquid becomes concave upward when angle of surface tension wit the vertical is less than 90o.

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