A point charge is placed at the centre of spherical Gaussian surface. Is electric flux `phi_(E)` changed if
(a) The sphere is replaced by a cube of same or different volume ?
(b) The charge is moved off-centre in the original sphere, still remaining inside ?
( c ) The charge is moved just outside the original sphere ?
(d) A second charge is placed near the outside to the origianl schere ?
(e) A second charge is placed inside the Gaussian surface ?

Explanation

For answering all these questions note that, "As per Gauss.s law the total electric flux over the surface is just dependent on the net charge enclosed and the flux is independent of the shape or size of the surface".
(a) `phi_(E)` is not changed because the net charge enclosed is same
(b)` phi_(E)` is not changed because the charge is still enclosed by the surface. The charge need not be at the centre
( c ) Now, the flux will become zero because the charge has gone out and no charge is enclosed by the surface
(d) The flux will not be changed because the new charge is outside the surface and net charge enclosed is still the same
(e) The flux now will change because the net charge enclosed has changed