When two soap bubbles of radius r1 and r2 (r2 > r1) coalesce, the radius of curvature of common surface is
Let 'r be the radius of common surface of two bubbles.
If ΔP1 and ΔP2 are the excess pressures in two soap bubbles of radius r1 and r2 andΔ P be the pressure difference between the bubbles after coalesce with each other.∴ΔP =ΔP1 −ΔP24Tr= 4Tr1− 4Tr21r = 1r1 −1r2r = r1r2r2−r1