A negative point charge of (-1) nC is located at the origin of a
coordinate system, and is surrounded by a surface charge density
spread out over a spherical surface centered on the origin of radius
25 cm. The charge density value is (+1) nC/m2.

Note: Please notice that the charge density has a unit nC/m2 while the
discrete point charge has a unit in nC only.

a) What components of the electric field should exist in this problem,
and what variables could they be functions of? Specify the coordinate
system you are using to answer this question.

b) Use Gauss?s law to find the electric field (magnitude and
direction) for observation points less than 25 cm from the origin.

c) Use Gauss?s law to find the electric field (magnitude and
direction) for observation points more than 25 cm from the origin.