If a dipole of dipole moment is placed in a uniform electric

Home » Electrostatics » Electric Charges and Fields » Question

If a dipole of dipole moment is placed in a uniform electric field , then torque acting on it is given by

1. τ^{^→} = p^{^→} . E^{^→}
2. τ^{^→} = p^{^→} × E^{^→}
3. τ^{^→} = p^{^→} + E^{^→}
4. τ^{^→} = p^{^→} - E^{^→}

Correct Option: B

Given : Dipole moment of the dipole = p^{^→} and uniform electric field = E^{^→} . We know that dipole moment (p) = q.a (where q is the charge and a is dipole length). And when a dipole of dipole moment ṗ is placed in a uniform electric field , then Torque (τ) = Either force × Perpendicular distance between the two forces = qaEsinθ or Τ = pE sin θ or Τ^{^→} = p^{^→} × E^{^→} (vector form)