Two soap bubbles coalesce. It is noticed that, whilst joined together, the radii of the two bubbles are a and b where a b . Then the radius of curvature of interface between the two bubbles will be

Step-by-step solution

According to given figure, Let the radius of curvature of the common internal film surface of the double bubble formed by two bubbles be r . Excess of pressure as compared to atmosphere inside A is (4 T / a) . In double bubble, the pressure difference between A and B on either side of the common surface = 4 T b - 4 T a This will be equal to ( 4 ~T / r ) 4 T r = 4 T b - 4 T a or 1 r = ( 1 b - 1 a )= a-b b a or r= a b a-b