A glass rod of radius `r_(1)` is inserted symmetrically into a vertical capillary tube of radius `r_(2)` such that their lower ends are at the same level. The arrangement is now dipped in water. The height to which water will rise into the tube will be (`sigma =` surface tension of water, `rho = ` density of water)

Options

A. `T/((R+r)rhog)`
B. `(Rrhog)/(2T)`
C. `(2T)/((R-r)rhog)`
D. `((R-r)rhog)/T`

Answer

C

Explanation

Rise of water in the capillary tube is given by
`h=(2Tcostheta)/(rhog(R-r)` [Symbols have their usual meanings]
in the given case
`costheta=1 as theta=0^circ`
So, `h=(2T)/(rhog(R-r)`