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Question
A liquid is contained in a vertical tube of semicircular cross section. The contact angle is zero. The force of surface tension on the curved part and on the flat part are in ratio
Options
1:1
1:2
π:2
2:π
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Solution
Let the height of the liquid-filled column be L.
Let the radius be denoted by R.
\[\text{ Total perimeter of the curved part = semi - circumference of upper area }= \pi r \]
\[\text{ Total surface tension force } = \pi RS\]
\[\text{ Total perimeter of the flat part = 2R } \]
\[\text{ Total surface tension force = 2RS }\]
\[\text{ Ratio of curved surface force to flat surface force } = \frac{\pi RS}{2RS} = \frac{\pi}{2}\]
\[\]
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