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Select the correct statement(s) about electrostatics. (A) Gauss's law is valid only for symmetric charge distributions. (B) An electric field line in the x-y plane is given by xy = 1. A unit positive charge released from rest at (1, 1) will move along this field line. (C) In electrostatic equilibrium, the magnitude of the electric field is the same at every point of a spherical conductor for a uniform charge distribution. (D) In electrostatic equilibrium, the electric potential is the same at every point of a conductor.

1. (A)
2. (B)
3. (C)
4. (D)

Correct answer: (D)

Solution

(A) FALSE: Gauss's law is universally valid; it is only easily solvable for symmetric distributions. (B) FALSE: a charge released from rest follows the field line at first, but because of inertia it will not track a curved field line exactly. (C) FALSE: inside the conductor E = 0, on the surface E is nonzero — not the same everywhere. (D) TRUE: in electrostatic equilibrium every point of the conductor (surface and interior) is at the same potential.

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