If the excess pressure inside a soap bubble of radius 5 mm is balanced by a 1.5 mm column of oil of specific gravity 0.76, find the surface tension of the soap solution.

If the excess pressure inside a soap bubble of radius 5 mm is balanced

1.	If the excess pressure inside a soap bubble of radius 5 mm is balanced by a 1.5 mm column of oil of specific gravity 0.76, find the surface tension of the soap solution.
Answer» Solution :Given, `r=5 mm =5 xx 10^(-3) m` `h=1.5 mm =1.5 xx 10^(-3) m` `p_("oil")=0.76 xx 10^(3)" kg/m"^(3)` Excess pressure inside a soap bubble with two free surface is `p=(4 sigma)/R` which is EQUAL to the PRESURE EXERTED by 1.5 mm COLUMN of oi. `p=HPG` `rArr (4 sigma)/(R)=hpg` `or sigma=(hpgR)/(4)` `=(1.5 xx 10^(-3) xx 0.76 xx 10^(3) xx 9.8 xx 5 xx 10^(-3))/(4)` `=13.96 xx 10^(-3) N//m`