Question 136 of 192

A capillary tube made of glass of radius $0.15mm$ is dipped vertically in a beaker filled with methylene iodide (surface tension $=0.05N{m}^{-1}$, density $=667kg{m}^{-3}$) which rises to height $h$ in the tube. It is observed that the two tangents drawn from observed that the two tangents drawn from liquid-glass interfaces (from opp. sides of the capillary) make an angle of $60º$ with one another. Then $h$ is close to ($g=10m{s}^{-2}$)

A$0.049m$B$0.087m$C$0.137m$D$0.172m$

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Answer: (B) $0.087m$

$h=\dfrac{2Tcos\theta }{\rho gr}\theta =30^{\circ}P=667kg{m}^{-3};T=1/20N{m}^{-1};r=0.15\times {10}^{-3}$

$=\dfrac{2\times \dfrac{1}{20}\times \dfrac{\sqrt{3}}{2}}{667\times 10\times 0.15\times {10}^{-3}}=0.087m$