Conductors contain mobile charge carriers. In
metallic conductors, these charge carriers are electrons. In a metal, the outer
(valence) electrons part away from their atoms and are free to move. These
electrons are free within the metal but not free to leave the metal.
In an external electric field, they drift against
the direction of the field. The positive ions made up of the nuclei and the
bound electrons remain held in their fixed positions. In electrolytic
conductors, the charge carriers are both positive and negative ions.
Important results regarding electrostatics of
conductors.
1.
Inside
a conductor, electrostatic field is zero
In the static situation, the free charges have so
distributed themselves that the electric field is zero everywhere inside.
Electrostatic field is zero inside a conductor.
2. At the surface of a charged conductor,
electrostatic field must be normal to the surface at every point
In the static situation, therefore, E should have
no tangential component. Thus electrostatic field at the surface of a charged
conductor must be normal to the surface at every point.
3. The interior of a conductor can have no
excess charge in the static situation.
There is no net charge at any point inside the
conductor, and any excess charge must reside at the surface.
4. Electrostatic potential is constant
throughout the volume of the conductor and has the same value (as inside) on
its surface
Since E = 0 inside the conductor and has no tangential component
on the surface, no work is done in moving a small test charge within the
conductor and on its surface. That is, there is no potential difference between
any two points inside or on the surface of the conductor.
5. Electric field at the surface of a charged conductor
where σ is the surface charge density and nˆ is a unit vector
normal to the surface in the outward direction.
why cant the charge reside inside a hollow conductor
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