If excess pressure is balanced by a column of oil (with specific gravity 0.8) 4 mm high, where R = 2.0 cm, Find the surface tension of the soap bubble.

Explanation

The excess of pressure inside the soap bubble is
`" " DeltaP = P_(2) - P_(1) = (4T)/R`
But `" " DeltaP = P_1 - P_1 = rho gh implies rho gh = (4T)/R`
`implies "surface tension" , T = (rho gh R)/4 = ((800)(9.8)(4 xx 10^(-3))(2 xx 10^(-2)))/(4)`
`T = 15.68 xx 10^(-2) Nm^(-1)`