Question

In vector form, how is the torque on an electric dipole in a uniform electric field expressed?

Options

• \[\vec{\tau}\] = \[\vec{E}\] × \[\vec{p}\]

• \[\vec{\tau}\] = \[\vec{p}\] · \[\vec{E}\]

• \[\vec{\tau}\] = \[\vec{p}\] × \[\vec{E}\]

• \[\vec{\tau}\] = \[\vec{p}\] + \[\vec{E}\]

Answer 1

The vector form of torque on a dipole is \[\vec{\tau}\] = \[\vec{p}\] × \[\vec{E}\], which is a cross product. This ensures that the torque is perpendicular to both the dipole moment and the electric field, and its magnitude is pE sin θ where θ is the angle between them. The direction is determined by the right-hand screw rule.