A glass capillary tube of inner diameter 0.28 mm is lowered vertically into water in a vessel. The pressure to be applied on the water in the capillary tube so that water level in the tube is same as that in the vessel (in `Nm^-2`) is Surface tension of water = `0.07 Nm^-1`
Atmospheric pressure = `10^5 Nm^-2`

Options

A. `10^3`
B. `99xx10^3`
C. `100xx10^3`
D. `101xx10^3`

Answer

A

Explanation

Surface tension
`T=0.07N//m`
`T=(rhgd)/(2costheta)`
For water `theta = 0^@`
`sigma = (r(hdg))/(2costheta) =(rp)/2`
`therefore P = (2T)/r = (2xx0.07)/(0.14 x 10^(-3)) = 1xx10^(3) N/m^(2)`
Total pressure = P + Atmospheric pressure
`1xx10^(3) + 10^(5)`
`101 xx 10^(3) Nm^(2)`