A container is partially filled with a liquid of density `rho_2` A capillary tube of radius r is vertically inserted in this liquid. Now another liquid of density `rho_1(rho_1ltrho_2)` is slowly poured in the container to a height h as shown. There is only denser liquid in the capillary tube. The rise of denser liquid in the capillary tube is also `h`. Assuming zero contact angle, the surface tension of heavier liquid is

Options

A. `r rho_(2) gh`
B. `2pirrho_(2) gh`
C. `r/2 (rho_(2)-rho_(1))gh`
D. `2pir(rho_(2)-rho_(1)) gh`

Answer

C

Explanation

`P_(0)+rho_(1)g h-rho_(2) g h +(2T)/r=P_(0)`
`rArr T=r/2 (rho_(2)-rho_(1)) gh`