Question

The work done by surface tension on rising water to height of $h$ in a capillary tube of radius $r$, is

• A. $\frac{2\pi T^2}{\rho }$
• B. $\frac{\rho g}{2\pi T^2}$
• C. $\frac{4\pi T^2}{\rho g}$
• D. None of these

Answer 1

The correct option is C $\frac{4\pi T^2}{\rho g}$

work done = $T\left(2\pi r\right)h$

$h=\frac{2T}{r\rho g}$

$\therefore W=T2\pi r\frac{2T}{r\rho g}=\frac{4\pi T^2}{\rho g}$