In a capillary tube of radius 0.2 mm the water rises up to height of 7.5 cm with angle of contact equal to zero. If another capillary with same radius but of different material dipped in the same liquid. The height of water raised in capillary will be, if angle of contact becomes `60^(@)`

Options

A. 7.5 cm
B. 15 cm
C. 3.75 cm
D. 30 cm

Answer

C

Explanation

If R=0.2 mm for two capillary
As in `1^(st)` case
h=7.5 cm
`T=(Rh rho g)/(2 cos theta) (theta=0)`
`=7.5 xx10^(-2)`
0.075 N/m
Now in `2^(nd)` case
`T=(Rh_(1)rhog)/(2 cos theta)(theta=60)`
`h_(1)=(2cos 60 xx7.5xx10^(-2))/(0.2xx10^(-3)xx10)`
`=7.5/2xx10^(-2)`
`=3.75xx10^(-2)`m
=3.75 cm
Alternate:
`T=(Rh rhog)/(2 cos theta)`
`7.5/100=(h')/(cos 60)`
`h'=3.75 cm`