The lower end of a capillary tube of radius r is placed vertically in water. Then with the rise of water in the capillary through height 'h'. heat evolved is : (Take d= density of water )

Options

A. `+ pi^2 r^2 h dg `
B. `+( pi^2 r^2 h^2)/(2) dg `
C. `-(pi r^2 h^2 )/(2) dg`
D. `pir^2 h^2 dg `

Answer

B