JEE Mains · Physics · STD 11 - 9.2 surface tension
A capillary tube made of glass of radius \(0.15\, mm\) is dipped vertically in a beaker filled with methylene iodide (surface tension \(=0.05\, Nm ^{-1},\) density \(\left.=667\, kg m ^{-3}\right)\) which rises to height \(h\) in the tube. It is observed that the two tangents drawn from liquid-glass interfaces (from opp. sides of the capillary) make an angle of \(60^{\circ}\) with one another. Then \(h\) is close to \(......m\) \(\left(g=10\, ms ^{-2}\right)\)
- A \(0.137\)
- B \(0.172\)
- C \(0.087\)
- D \(0.049\)
Answer & Solution
Correct Answer
(C) \(0.087\)
Step-by-step Solution
Detailed explanation
\(r \rightarrow\) radius of capillary \(R \rightarrow\) Radius of meniscus. From figure, \(\frac{r}{R}=\cos 30^{\circ}\) \(R =\frac{2 r }{\sqrt{3}}=\frac{2 \times 0.15 \times 10^{-3}}{\sqrt{3}}\) \(=\frac{0.3}{\sqrt{3}} \times 10^{-3} m\) Height of capillary…
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