The dimensions of an atom are of the order of an Angstrom. Thusthere must be large electric fields between the protons and electrons.Why, then is the electrostatic field inside a conductor zero?NCERT Class XIIPhysics - Exemplar Problems Chapter 1. Electric Charges and Fields



The electrostatic field inside a conductor is zero because the electrostatic field is due to the excess change.
Atoms are electrically neutral.
Hence there is excess change on the atom.If the charge is zero, then, E= \frac{1}{4 \pi  E_{o} }  \frac{q}{ r^{2} }
Since q=0,E=0