Why does the water rise in a capillary tube? Explain.

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(N/A) The rise of a liquid in a capillary tube is governed by the formula $h = \frac{2S \cos \theta}{r \rho g}$,where $S$ is the surface tension,$\theta$ is the angle of contact,$r$ is the radius of the capillary,$\rho$ is the density of the liquid,and $g$ is the acceleration due to gravity.
For water in a glass capillary,the angle of contact $\theta$ is acute (i.e.,$\theta < 90^{\circ}$),which makes $\cos \theta$ positive.
Since $S, r, \rho,$ and $g$ are all positive constants,the height $h$ becomes positive,indicating that the liquid level rises inside the capillary tube to balance the pressure difference caused by the curved meniscus.

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