1. The problem statement, all variables and given/known data A particle having charge q = 8.85 μC is placed on the axis of a circular ring of radius R = 30 cm. Distance of the particle from centre of the ring is a = 40 cm. Calculate electrical flux passing through the ring. 2. Relevant equations Flux through a surface = ∫E.ds 3. The attempt at a solution I have tried to sketch a figure . Since the circle is not a closed surface .I tried to make the spherical cap whose base is the given circle . Then I completed that sphere . Now I think flux through the circle is equal to the flux through the spherical cap .But then what is the flux through the spherical cap ? Is the ratio of the surface area of the cap to that of the sphere same as the ratio of the flux across these two surfaces ? I would appreciate if somebody could help me with the problem .