A point charge is placed at the centre of spherical gaussian surface. How will the total electric flux change if an identical is placed is placed very closed to it (a) inside the gaussian sphere (b) outside the gaussian sphere.
Answers
#BAL
By gauss' law, the net flux is zero, as the net charge inside is zero. This is clear from that fact that as you know, all the field lines originating on the positive part of the dipole end up on the negative part of the dipole, and so the number of lines leaving and entering the surface is the same.
Note: I cheated a little there. All the lines from the positive charge end up on the negative charge ONLY if the dipole is an isolated system. If there are other charges nearby, in truth, some of the lines from the positive charge will terminate outside the sphere. So how is gauss’ law still valid? This will be compensated by the rearrangement of other field lines. It helps to look at computer generated field line diagrams to help understand how this compensation works.