A soap film is made by dipping a circular frame of radius $b$ in soap solution. A bubble is formed by blowing air with speed $v$ in the form of cylinder. The radius of the bubble formed $R \gg b$ so that the air is incident normally on the surface of bubble. Air stops after striking surface of soap bubble. Density of air is $\rho $. The radius $R$ of the bubble when the soap bubble separates from the ring is (surface tension of liquid is $S$)