Question

A capillary tube of radius 0.50 mm is dipped vertically in a pot of water. Find the difference between the pressure of the water in the tube 5.0 cm below the surface and the atmospheric pressure. Surface tension of water `=0.075Nm^-1`

Answer 1

Correct Answer - A::B
`r=0.5mm=5xx10^-3m`
`h=5.0mm=5xx10^-2m`
`T=0.075N/m`
the excess pressure at `5cm` before the surface
`P=hrhog=100x(5x10^-2)x9.8`
`=490N/m^2`
Again excess pressure at the surface
`P=(2T)/r=(2xx(0.75))/((5xx10^-4))`
`=300N/m^2`
diffeeence in pressure
`=P=(F/r)`
`=490-300=190N/m^2`