Question

Water rises upto a height 10 cm in a capillary tube. It will rise to a height which is much more than 10 cm in a very long capillary tube if the apparatus is kept.

• A. on the surface of the moon.
• B. at the north pole.
• C. in a lift moving up with an acceleration.
• D. on the equator.

Hint:

Capillary rise \(h \propto 1/g\). Height increases when effective gravity decreases.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
Capillary rise height \(h = \frac{2S \cos \theta}{\rho g r}\). Height is inversely proportional to effective gravity \(g\).

Step 2: Key Formula or Approach:
If effective gravity decreases, height increases. If effective gravity increases, height decreases.

Step 3: Detailed Explanation:
In a lift moving up with acceleration \(a\), effective gravity = \(g + a\) (greater than \(g\)). This would decrease the height, not increase it. Thus, the rise will be much more than 10 cm in a lift moving up with an acceleration.

Step 4: Final Answer:
Option (C) is correct.