Which of the following statements are true for a conductor in an exte…

The correct answer is Option (4) → (B), (C) and (D) only

(A) Inside a conductor, the electric field is non-zero. — Incorrect. A non-zero field would drive the free charges, so in the static situation the field inside is zero.

(B) At the surface of a charged conductor, the electric field must be normal to the surface at every point. — Correct. A component along the surface would move the surface charges, so the static field has only a normal component.

(C) The interior of a conductor can have no excess charge in a static situation. — Correct. With \( \vec{E} = 0 \) inside, Gauss's law gives no net charge inside, so any excess charge lies on the surface.

(D) Electrostatic potential is constant throughout the volume of the conductor and has the same value on its surface. — Correct. Since \( \vec{E} = 0 \) inside, no work is done in moving a charge between two points, so the whole conductor is an equipotential.

Statements (B), (C) and (D) are correct, which is Option (4).

NCERT (2026-27):
Electrostatics of Conductors – “… In the static situation, the free charges have so distributed themselves that the electric field is zero everywhere inside. Electrostatic field is zero inside a conductor.”

Electrostatics of Conductors – “… Thus electrostatic field at the surface of a charged conductor must be normal to the surface at every point.”

Electrostatics of Conductors – “… This means there is no net charge at any point inside the conductor, and any excess charge must reside at the surface.”

Electrostatics of Conductors – “… That is, there is no potential difference between any two points inside or on the surface of the conductor.”