Question

The potential energy of a dipole in an external electric field is given by:

Options

• \[U = -pE \cos\theta = -\vec{p} \cdot \vec{E}\]

• \[U = pE \sin\theta\]

• \[U = pE\]

• \[U = pE \cos\theta\]

Answer 1

The potential energy of a dipole in an external electric field \[\vec{E}\] is defined as \[U = -pE \cos\theta = -\vec{p} \cdot \vec{E}\], where θ is the angle between the dipole moment and the field. This formula is derived by taking the zero potential energy reference at θ = 90° (perpendicular orientation) and integrating the work done against the torque.