If the excess pressure inside a soap bubble of radius 5 mm is equal to the pressure of a water column of hight 0.8 cm, then the surface tension of the soap solution will be

Options

A. 980 N/m
B. `98 xx10^(-2)`N/m
C. `98 xx10^(-3)` N/m
D. 98 N/m

Answer

C

Explanation

Excess pressure ` = (4T)/R`
and hydrostatic pressure = `hrho g`
` :. (4T)/R = hrho g`
` :. T = (h rho gR)/4 " " [ rho _("water") = 1000 kg//m^(3)]`
` (8xx10^(-3) xx10^(3)xx9.8xx5 xx10^(-3))/4`
` T = 98 xx10^(-3)N//m`