Two parallel glass plates separated by a small distance x are dipped partly in a liquid of density " d" keeping them vertical .The surface tension of the liquid is T and angle of contact is `theta ` . What is the rise of the liquid between the plates due to capillarity ?

Options

A. `(T cos theta)/(xd)`
B. `(2T cos theta)/(xdg)`
C. `(2T)/(xdg cos theta)`
D. `(T cos theta)/(xdg)`

Answer

B

Explanation

Let the width of each plate is b and due to surface tension liquid will rise upto height h, then upward force due to surface tension `= 2Tb cos theta`

Weight of the liquid eises in betweent the plates
= Vdg = (bxh)dg
Equating Eqs. (i) and (ii), we get
`2Tb cos theta = bxhdg`
`therefore" "h=(2T cos theta)/(xdg)`