A glass capillary of radius 0.4 mm is inclined at `60^(@)` with the vertical in water. Find the length of water in the capillary tube.
(Given, surface tension of water `= 7 xx 10^(-2) N^(-1)`).

Options

A. 7.1 cm
B. 3.6 cm
C. 1.8 cm
D. 0.9 cm

Answer

A

Explanation

Use, `h = l cos alpha`
`rArr l = (h)/(cos alpha)`
where, `h = (2S cos theta)/(rho rg) " "(theta_("water" = 0^(@)))`
`:.` The length of water in capillary tube
`l = (2S cos theta)/(rho rg cos alpha) = (2 xx 7 xx 10^(-2) cos 0^(@))/(10^(3) xx 0.4 xx 10^(-3) xx 9.8 cos 60^(@))`
`= 7.1 cm`