Question

Two charges of magnitude + 4 q and -q are located at point (a,0) and (-3a,0) respectively what is the electric flux due to this charges through a sphere of radius 2a with its centre at the origin

Answer 1

if the points are in xy- plane.

centre of the sphere is origin.

radius of the sphere = 2a

so, point (a,0) will lie inside the sphere and point (-3a,0) will lie outside the sphere.

flux due to charge at point (-3a,0) = 0

flux due to charge at point (a,0) = 4q/€0

so, net flux through the sphere = 4q/€0

hope, it helped you.