Basic principle of electrostatics?

[planesinspace]

I seem to be having trouble grasping a very basic principle in electromagnetism. I have been told, in numerous places, that the electric field inside a conductor is zero. (Electrostatics). Yet I keep coming across problems in the textbook like this one:

"Use Gauss's Law to find the electric field inside a uniformly charged sphere (charge density 'ro')."

where for Q[enclosed] = charge density * volume

However, don't all the charges move to the surface of the sphere? and the electric field IN the sphere is subsequently zero?

 

[Feldoh]

uniformly charged sphere =/= conductor in all cases.

 

[Studiot]

the electric field inside a conductor is zero. (Electrostatics).

Yes this is true so long as there is not current flowing - all charges are stationary.

As soon as a current flows there is a field.

 

[ZapperZ]

Yes this is true so long as there is not current flowing - all charges are stationary.

As soon as a current flows there is a field.

The OP did indicate that this is Electrostatics. So there is no need to make such qualification.

Feldoh has sufficiently answered the question here, that just because one has a spherical charge, it doesn't mean that one also has a conducting sphere.

Zz.

 

[sardar]

The basic principle of electrostatics is that in a conductor, the electric field inside the material is zero. This means that the electric charges within the conductor are distributed in such a way that they cancel out each other's electric fields, resulting in a net zero field inside the material.

In the example you provided, the electric field inside the uniformly charged sphere is zero because the charges are evenly distributed throughout the volume of the sphere. This means that the electric field at any point inside the sphere would be canceled out by the surrounding charges.

It is important to note that although the electric field inside the conductor is zero, the charges are still present and can move freely within the material. This is why the charges can redistribute themselves to the surface of the sphere in your example.

I would recommend reviewing the concept of Gauss's Law, which states that the flux (flow) of the electric field through a closed surface is proportional to the enclosed electric charge. In the case of a uniformly charged sphere, the enclosed charge is not zero, which is why Gauss's Law can still be applied to find the electric field outside the sphere.

I hope this helps clarify the concept for you. If you have any further questions, please don't hesitate to ask.