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STD 11 - 9.2 , surface tension — JEE STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 ScienceJEESTD 11 - 9.2 , surface tension4 Marks
MCQ
Along capillary tyube of radius $ ‘r’$ is initially just vertically completely imerged inside a liquid of angle of contact $0^o $. If the tube is slowly raised then relation between radius of curvature of of miniscus inside the capillary tube and displacement $(h)$ of tube can be represented by
  • A

  • ✓

  • C

  • D

✓

Answer

Correct option: B.

b
The curvature equation relating the radius of meniscus inside the capillary tube and the displacement of the tube is given by,

$H=\frac{1}{2} \times\left(\frac{1}{R_{1}}+\frac{1}{R_{2}}\right)$

For a hemispherical, meniscus (which is the case for $0^{\circ}$ contact angle liquid,

$R_{1}=R_{2}=r$

Substituting the values in the equation,

$\mathrm{H}=\frac{1}{r}$

Thus, the graph should resemble a hyperbolic parabola with a value r at a displacement

$\mathrm{h}$

Hence, option $B$

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