The work done by surface tension on rising water do height of `h` in a capillary tube of radius `r` is

Options

A. `(2piT^(2))/(rho g)`
B. `(rho g)/(2pi T^(2))`
C. `(4 pi T^(2))/(rho g)`
D. `(2 pi T^(2))/(rho)`

Answer

C

Explanation

As we know that the work done by surface tension is given by
`W=2pirTh`…………..i
As `h=(2Tcos theta)/(rhog)` where `rho` is the density of water.
For water `theta=0^(@)`
`:.h=(2T)/(r rhog)`
Subsituting this value of `h` in Eq. (i) we get
`W=2pi rT((2T)/(rho rg))=(4piT^(2))/(rho g)`