Two spherical soap bubbles of radii a and b in vacuum coaleasce under isothermal conditions. The resulting bubbles has a radius given by

Step-by-step solution

Since the bubbles coalesce in vacuum and there is no change in temperature, hence its surface energy does not change. This means that the surface area remains unchanged. Hence 4 a^2+4 b^2=4 R^2 or R= a^2+b^2