The excess pressure inside a soap bubble of radius 6mm is balanced by 2mm column of oil of specific gravity .8. find the surface tension of the soap solution.
The excess pressure inside the bubble
dP = 4T /r
The pressure to height column of oil
P = hρg
Since the excess pressure inside the bubble is balance by the height of the column:
4T/r = hρg
or, T = rhρg / 4
or, T = (0.6 x 0.2 x 0.8 x 980) / 4
or, T = 23.52 dyne/cm