Rankers Physics

Surface Tension and Viscosity: Practice Problem & Solution

Water rises to height '$h$' in capillary tube. If the length of capillary tube above the surface of water is made less than '$h$', then: (2015 Re)
Water does not rise at all.
Water rises up to the tip of capillary tube and then starts overflowing like a fountain.
Water rises up to the top of capillary tube and stays there without overflowing.
Water rises up to a point a little below the top and stays there.

Solution Explained:

To solve this problem, we apply the core principles of Surface Tension and Viscosity. Understanding the underlying formula is key to arriving at the correct answer below:

When a capillary tube is of insufficient length, the liquid rises to the top and changes its meniscus radius to maintain equilibrium ($hR = \text{constant}$). It does not overflow.

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