Q 11-09-025NEETJEE MainMedium
In a capillary tube water would rise to $6$ cm, but the tube sticks out only $4$ cm above the water surface. Then
Answer: (C) water rises to the top and stops, with a meniscus of larger radius
Concept. $hR = \dfrac{2T}{\rho g}$ is fixed, where $R$ is the meniscus radius of curvature.
Step 1. Short tube. With $h$ limited to $4$ cm, the meniscus flattens (its radius grows to $\dfrac64$ of normal). Nothing supplies energy for a continuous flow, so there is no overflow.
Answer. Water rises to the top and stops, with a meniscus of larger radius (Option C).
Solution by Sreeraj P, M.Sc Physics