Target Exam

CUET

Subject

Physics

Chapter

Electrostatic Potential and Capacitance

Question:

An electric dipole is placed in a uniform electric field. Its potential energy will be minimum when the angle between its dipole moment and the electric field is

Options:

90°

180°

30°

Correct Answer:

Explanation:

The correct answer is Option (1) → 0°

Potential energy of a dipole in a uniform electric field is given by:

$U = -\vec{p} \cdot \vec{E} = -pE \cos\theta$

where $\theta$ is the angle between the dipole moment $\vec{p}$ and the electric field $\vec{E}$.

Potential energy is minimum when $\cos\theta$ is maximum, i.e., $\cos\theta = 1$

⇒ $\theta = 0^\circ$

∴ The potential energy is minimum when the dipole moment is parallel to the electric field, i.e., $\theta = 0^\circ$