[Physics] Electrostatics of hollow conductors

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My textbook says:

  • Inside a conductor, electric field is zero.
  • The interior of a conductor can have no excess charge in static situation.
  • Electric field just outside a charged conductor is perpendicular to the surface at every point.

I know that these laws are meant for solid conductors or in other words conducting materials alone. But if we had a hollow spherical conducting sphere maybe with air (or any insulator) as the medium inside the sphere, how would these laws be affected if a positive charge ( or any charge for that matter) is placed inside the sphere in air (static condition).

Best Answer

The macroscopic electric field inside the 'metal' of the conductor is zero in electrostatic conditions. In a hollow cylinder , if a positive charge is place inside the cavity, the field is non zero inside the cavity.

Again, the interior of a hollow shell can hold the positive charge there, because of the induced charges on the inner wall of the cavity. These charges, nullify the field due to the positive charge inside the 'metal' of the conductor. The last conclusion is always true in electrostatic conditions, when the conductor becomes an equipotential.