Mercury has an angle of contact equal to `140^(@)` with soda lime glass . A narrow tube of radius `1.00` mm made of this glass is dipped in a trough containing mercury .By what amount does the mercury dip down in the tube relative to the liquid surface outside ? Surface tension of mercury at the temperature of the experiment is `0.465Nm^(-1)` . Density of mercury `=13.6xx10^(3)kgm^(-3)`

Explanation

Here , angle of contact `theta=140^(@)`
Radius of narrow tube `r=1mm=10^(-3)m`
Surface tension `T=0.465Nm^(-1)`
Density of mercury `rho=13.6xx10^(3)kgm^(-3)`
Height of liquid in narrow tube of radius r,
`h=(2Tcostheta)/(rrhog)`
`=(2xx0.465xxcos140^(@))/(10^(-3)xx13.6xx10^(3)xx9.8)`
`=0.00534498`
`=-5.34xx10^(-3)m`
Negative sign shows that the mercury level is depressed in the tube.