Three charges +2q, +3q and −4q are situated at (0,−3a), (2a,0) and (−2a,0) respectively in the xy plane. The resultant dipole moment about origin is
(A)2qa(3j^−i^)
(B)2qa(3i^−7j^)
(C)2qa(7i^−3j^)✓ Correct
(D)2qa(3j^−7i^)
Answer: (C)
Solution
The dipole moment about the origin is p=∑qiri. The charge +2q at (0,−3a) contributes 2q(−3a)j^=−6qaj^; the charge +3q at (2a,0) contributes 3q(2a)i^=6qai^; the charge −4q at (−2a,0) contributes (−4q)(−2a)i^=8qai^. Adding the components, p=(6qa+8qa)i^−6qaj^=14qai^−6qaj^. The resultant dipole moment about the origin is 2qa(7i^−3j^).
JEE Main · 2026 · 24 Jan 2026 · Shift 1 · Single correct option