4
6
Due to the spherical symmetry of the charge distribution, the E-field inside the charged ball must point
along radial direction (see red arrows in diagram)
E
dA
The dA vectors (blue arrows in above diagram) point perpendicular to the GS and are therefore parallel to E.
Again, E must point radially due to spherical symmetry
E
dA
Again the dA vectors are perpendicular to
the surface of the GS and
therefore parallel to E
dA
dA
E