Question

When a capillary tube is dipped in a liquid, the liquid rises to a height $h$ in the tube. The free liquid surface inside the tube is hemispherical in shape. The tube is now pushed down so that the height of the tube outside the liquid is less than $h$. Then

• A. the liquid will come out of the tube like in a small fountain
• B. the liquid will ooze out of the tube slowly
• C. the liquid will fill the tube but not come out of its upper end
• D. the free liquid surface inside the tube will not be hemispherical

Answer 1

Answer: (C), (D)

The correct options are
C the liquid will fill the tube but not come out of its upper end
D the free liquid surface inside the tube will not be hemispherical

Options A and B: Incorrect



In both cases, if water comes out then this water can be used to generate electricity and we will get free energy which is impossible.

Options C and D: Correct
Left diagram is of the capillary rise. In this case, the adhesive force is much more as compared to the cohesive force due to this more number of the molecule of liquid are attracting by the molecules of the tube so they will try to rise on the boundary and will create hemisphere.
(Right diagram) But if the tube is pushed down then the adhesive force will decrease as the free molecule of the tube above liquid level are less. So liquid molecules are not attracted by surface. So it will also not be hemispherical.