Capillary Rise under Different Conditions – Rankers Physics

Surface Tension and Viscosity: Practice Problem & Solution

A long capillary is dipped in a beaker containing water. Water rises in capillary upto some height \(h\). Match the statements in list-I with most appropriate effects on water level mentioned in list-II: **List-I** (A) Soap solution is added to water (B) Arrangement taken in a freely falling lift (C) In a lift accelerating uniformly upward (D) Arrangement is taken in a lift accelerating uniformly downward **List-II** (p) \(h\) decreases (q) \(h\) increases (r) \(h\) remains same (s) water will rise upto complete height of capillary (t) water level in capillary goes below the outside level  
A - p, B - t, C - q, D - p
A - t, B - q, C - s, D - p
A - p, B - s, C - p, D - q
A - q, B - p, C - s, D - q

Short Solution (Best for NEET):

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:

Soap reduces surface tension, so \(h\) decreases (A-p). In a free fall, effective gravity \(g_{eff} = 0\), so water rises to full height (B-s). Upward acceleration increases \(g_{eff}\) hence \(h\) decreases (C-p). Downward acceleration decreases \(g_{eff}\) hence \(h\) increases (D-q).

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