Given below are two statements.
Statement I : Electric potential is constant within and at the surface of each conductor.
Statement II : Electric field just outside a charged conductor is perpendicular to the surface of the conductor at every point.
In the light of the above statements, choose the most appropriate answer from the options given below.

Solution

Physics sir · 4 steps

Inside a conductor in equilibrium E = 0. Both statements follow from that one fact.

1. Field inside is zero. In electrostatic equilibrium the free charges in a conductor have stopped moving. That can only happen if the field everywhere inside the material is E = 0.
2. Statement I. Potential difference between two points is -∫ E⃗ · dl⃗. With E = 0 inside, every point inside and on the surface has the same potential. The whole conductor is an equipotential, so Statement I is correct.
3. Statement II. If the field just outside had a component along the surface, it would push the surface charges sideways and they would move. In equilibrium they do not move, so the field has no tangential part and is perpendicular to the surface at every point. Statement II is correct.
4. So. Both statements are correct, which is option (a).

The idea to keep. For any conductor in electrostatics: E = 0 inside, the whole body is one equipotential, and the field just outside meets the surface at right angles.

Answer from the NTA final answer key. Solution by PrepWiser.