Question

The figure above shows two charged spherical conductors, X and which are equal in size. When each conductoris isolated and surrounded by a closed cubical surface, the total electric flux through the surfaces is for conductor X and -40 for conductor Y

Answer 1

1. As the electric flux always goes from positive charge to negative charge, the more the charge, the more the flux. Now the flux through a gaussian surface(cubical here) remains the same if the charge it contains doesn't change. So if Y is brought closer to cube(not inside it) that contains X, then also the total flux through the cube would be the same, but the flux through the surface near which the Y is brought will be denser than others. Hence flux through other surfaces will also change while keeping the total flux through all surfaces unchanges.

So option E is correct.

2. If Y is taken far away from X, then also the flux will be same due to the same reason as mentioned above. So option D is correct.

3. The flux through a surface depends on the charge it surrounds, So if X and Y are brought into same box, the total flux will be just the scalar addition of two flux i.e. $\phi$ 0 - 4$\phi$0 = -3$\phi$0. Option A is correct