At the surface of a charged conductor electrostatic field must be normal to the surface at every point'. Explain.

Explanation

If `vecE` were not normal to the surface, it would have some non-zero component along the sudace. Free charges on the surface of the conductor would then experience force and move. Hence, conductor does not remains in stable siluation.
Therefore `vecE` should have no tangential component pardllel lo the surface in stable situation.
Thus, electrostatic field at the surface of a charged conductor must be normal to the surface at every point. (For a conductor without any surface charge density, field is zero even at the surface).