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Question
A 20 cm long capillary tube is dipped in water. The water rises up to 8 cm. If the entire arrangement is put in a freely falling elevator, the length of water column in the capillary tube will be
Options
8 cm
6 cm
10 cm
20 cm
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Solution
\[\text{ Height of water column in capillary tube is given by: } \]
\[h = \frac{2Tcos\theta}{r\rho g}\]
\[\text{ A free falling elevator experiences zero gravity }. \]
\[ \Rightarrow h = \frac{2Tcos\theta}{r\rho0} = \infty \]
\[\text{ But, h = 20 cm (given)}\]
\[\text{ Therefore, the height of the water column will remain at a maximum of 20 cm} .\]
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