Question

In given fig., an equilateral triangle ABC of side α has charges +2q, -q and -q at the vertices A, B and C respectively. Calculate the dipole moment of this system.

Answer 1

Give arrangement is equivalent to two electric dipoles AB and AC, which are at 60° to each other.
The dipole moment of electric dipole AB
P₁ = qα (along BA)
The dipole moment of electric dipole CA
p₂ = qα (along CA)

Resultant of electric dipole moment of p₁ and p₂

The direction of electric dipole moment PR is along half of the angle between p₁ and p₂ due to the equal vectors.