If one penetrates a uniformly charged hollow sphere, What will be the Electric field strength E and why? I know that, in the center of a uniformly charged hollow sphere, the electric field strength E will be zero. 
Exact question:
If one penetrates a uniformly charged hollow sphere, then the electric field strength E
(a) increases
(b) decreases
(c) remains the same as at the surface
(d) is zero at all points
Though I have tried a lot, I cannot understand it. I think if a uniformly charged hollow sphere is penetrated, there will be some electric field line in the center.
Am I right or wrong? What is the answer of the above problem? Please, Explain the logic behind it.
 A: Since the charge is uniform, they will be symmetrically arranged and the field vectors will cancel inside the sphere (at all points). In this case, the symmetry is the only thing that matters.
If you think of a more general case, where a bunch of charges are free to move on a conductor closed surface, they will move around until all forces are balanced. In this equilibrium situation, the electric field inside the conductor is also zero.
In the sphere case, if the charges were free to move along the surface, they would be uniformly arranged when in equilibrium.
A: If you're talking $\mod{E}$ then it will have to increase (the lowest value it can take is 0. There's no other option for it. I suspect that due to the symmetry there's probably still be a significant portion of it at 0 though. And for problems like this the calculations become rapidly complex and require numerical analysis rather. If the whole is small enough you can approximate that it's not there and then it would be essentially 0. 
A: According to Newton's shell theorem, which also hold for an electrostatic field caused by charges according to Coulomb's law, the electric field inside a homogeneously charged sphere must be zero. Thus, when you penetrate the surface of the uniformly charged sphere the electrical filed inside the sphere will go from a maximum value at the surface to zero inside the surface.
