Identify the correct statements among the following:
(A) An electric dipole is a pair of two equal and similar charges placed apart at a very short distance.
(B) Electric dipole moment is a vector quantity.
(C) Electric field produced by a dipole varies inversely with the square of the distance from its center on the axial line.
(D) If two charges, +q and −q, are placed at a very small distance d apart, then the magnitude of electric dipole moment is = qd
Choose the correct option from the following:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → (B) and (D) only
An electric dipole is a pair of equal and opposite charges separated by a small distance; its dipole moment points from the negative to the positive charge.
(A) An electric dipole is a pair of two equal and similar charges placed apart at a very short distance. — Incorrect. The charges must be opposite in sign, +q and −q.
(B) Electric dipole moment is a vector quantity. — Correct. It has magnitude qd and a direction from −q to +q.
(C) Electric field produced by a dipole varies inversely with the square of the distance from its center on the axial line. — Incorrect. For large r the axial field falls as the inverse cube of the distance.
\( \displaystyle E_{\mathrm{axial}} = \frac{1}{4\pi\varepsilon_0}\frac{2p}{r^{3}} \)
(D) If two charges, +q and −q, are placed at a very small distance d apart, then the magnitude of electric dipole moment is = qd — Correct. The dipole moment is either charge times the separation.
NCERT (2026-27):
Summary – “… 11. An electric dipole is a pair of equal and opposite charges q and –q separated by some distance 2a. Its dipole moment vector p has magnitude 2qa and is in the direction of the dipole axis from –q to q.”
Summary – “… The 1/r3 dependence of dipole electric fields should be noted in contrast to the 1/r2 dependence of electric field due to a point charge.”