Why should electrostatic field be zero inside a conductor ?

The dimensions of an atom are of the order of an Angstrom. Thus there must be large electric fields between the protons and electrons. Why, then is the electronstatic field inside a conductor zero?

The electric field inside a conductor

Cavity inside a conductor

Why is electric field intensity inside a charged conductor zero ?

Why is the electrostatic potential inside a charged conducting shell constant throughout the volume of the conductor?

When a 40 Vm^(-1) - electric field is produced inside a conductor then 2xx10^(4) Am^(-2) ? current density is established in it. Resistivity of the conductor is

When a 40 Vm^(-1) electric field is produced inside a conductor then 2 xx 10^(4) Am^(-2) current density is established in it . Resistivity of the conductor is .

The electrostatic field due to a charged conductor just outside the conductor is

A conductor is moving with velocity v in a region of uniform magnetic field B.The electric field at P inside conductor is