Equation for Electric Dipole in Uniform Electric Field - QS Study
QS Study

Electric Dipole in Uniform Electric Field:

Consider a dipole AB of dipole moment p placed at an angle θ in an uniform electric field E (Figure). The charge +q experience a force qE in the direction of the field. The charge –q experiences an equal force in the opposite direction. Thus the net force on the dipole is zero.

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The two equal and unlike parallel forces are not passing through the same point, resulting in a torque on the dipole, which tends to set the dipole in the direction of the electric field.

The magnitude of torque is,

τ = One of the forces x perpendicular distance between the forces

= F x 2d sin θ

= qE x 2d sin θ = pE sin θ (q * 2d = P)

In vector notation, τ = P * E