MCQ
Two capillary tubes of same diameter are put vertically one each in two liquids whose relative densities are $0.8$ and $0.6$ and surface tensions are $60$ and $50$ dyne/cm respectively Ratio of heights of liquids in the two tubes $\frac{{{h_1}}}{{{h_2}}}$ is
  • A
    $\frac{{10}}{9}$
  • B
    $\frac{3}{{10}}$
  • C
    $\frac{{10}}{3}$
  • $\frac{9}{{10}}$

Answer

Correct option: D.
$\frac{9}{{10}}$
d
(d) Ascent formula $h = \frac{{2T\cos \theta }}{{rdg}}$ 

$ \Rightarrow \frac{{{h_1}}}{{{h_2}}} = \frac{{{T_1}}}{{{T_2}}} \times \;\frac{{{d_2}}}{{{d_1}}}$          ($r,\;\theta $ and $g$ are constants) 

$ \Rightarrow \frac{{{h_1}}}{{{h_2}}} = \frac{{60}}{{50}} \times \frac{{0.6}}{{0.8}} = \frac{9}{{10}}$

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