Question

The lower end of a capillary tube is dipped in water. Water rises to a height of 8 cm. The tube is then broken at a height of 6 cm. The height of water colume and angle of contact will be
A. `6cm, sin^(-1)((3)/(4))`
B. `6cm, cos^(-1)((3)/(4))`
C. `4cm, sin^(-1)((1)/(2))`
D. `4cm, cos^(-1)((1)/(2))`

Answer 1

Correct Answer - B
When a capillary tube is broken at a height of 6 cm, the height of water column will be 6 cm.
As `h=(2S cos theta)/(r rho g)`
or `(h)/(cos theta) =(2S)/(r rho g)=a` constant
`:. (8)/(cos theta^(@)) =(6)/(cos theta)` or `cos theta =(6 cos 0^(@))/(8) =(3)/(4)`
or `theta=cos^(-1)(3//4)`