Question

Two parallel glass plates are dipped partly in a liquid of density ${}^{\prime }{d}^{\prime }$ keeping them vertical. If the distance between the plates is ${}^{\prime }{x}^{\prime }$ Surface tension for liquid is $T$ & angle of contact is $\theta$ then rise of liquid between the plates due to capillary will be

• A. $\frac{T\cos \theta }{xd}$
• B. $\frac{2T\cos \theta }{xdg}$
• C. $\frac{2T}{xdg\cos \theta }$
• D. $\frac{T\cos \theta }{xdg}$

Answer 1

The correct option is B $\frac{2T\cos \theta }{xdg}$

weight of liquid of height 'h' = (area of tube x h) x g x d= (3.14/4)hdg$x^2$

vertical component of surface tension force=(1/2)x(Txcircumference)x cosθ=3.14Txcosθ

therefore, (3.14/4)hgd$x^2$=(1/2)Tx3.14xcosθ

h=(2Tcosθ)/(gdx)

θ
θθs=Tx3.14x