Why is there never any electric field in a hollow conductor?

[animboy]

I can understand that if there is no charge inside an object then the electric FLUX is zero. Meaning the net integral of field vectors with respect to the area will be zero. But that doesn't mean there are no field lines inside the object at all! does it? I thought it just meant that the number of field lines going in equals the number of field lines coming out. But my lecturer drew it as if the field lines were instantly cut off when in in contact with the surface. Please explain this.

 

[mathfeel]

I can understand that if there is no charge inside an object then the electric FLUX is zero. Meaning the net integral of field vectors with respect to the area will be zero. But that doesn't mean there are no field lines inside the object at all! does it? I thought it just meant that the number of field lines going in equals the number of field lines coming out. But my lecturer drew it as if the field lines were instantly cut off when in in contact with the surface. Please explain this.

There are charges induced on the surface of the conductor, which is such that it screens out the electric field on the other side. So the electric field is cut off.

Rule of thumb: whenever you see discontinuity of electric field, there's some charge there.

 

[Naty1]

Note in the above post mention of a CONDUCTOR...so charge redistributes on the surface.

Your statement implies electrostatic conditions...no surface currents flowing on the conductor. ...so maybe the charge density on the conductor varies from point to point, but the field E is at right angles to the surface in the static condition. Otherwise there would be an induced voltage...and charge on the conductor would be redistributed...there would be surface currents.