Question

Three charges of (+2q), (– q) and (– q) are placed at the corners A, B and C of an equilateral triangle of side a as shown in the adjoining figure. Then the dipole moment of this combination is

• A. qa
• B. Zero
• C. $qa\sqrt{3}$
• D. $\frac{2}{\sqrt{3}}qa$

Answer 1

Answer: (C)

$qa\sqrt{3}$

Answer 2

The charge +2q can be broken in +q, +q. Now as shown in figure we have two equal dipoles inclined at an angle of 60^o. Therefore resultant dipole moment will be

$p_{net} = \sqrt{p^{2} + p^{2} + 2pp\cos 60} = \sqrt{3}p$

$= \sqrt{3}qa$