Question

An electric dipole with dipole moment 5 × 10⁻⁶ C m is aligned with the direction of a unifrom electric field of magnitude 4 × 10⁵ N/C. The dipole is then rotated through an angle of 60° with respect to the electric field. The change in the potential energy of the dipole is ______.

Options

• 0.8 J

• 1.0 J

• 1.2 J

• 1.5 J

Answer 1

An electric dipole with dipole moment 5 × 10⁻⁶ C m is aligned with the direction of a unifrom electric field of magnitude 4 × 10⁵ N/C. The dipole is then rotated through an angle of 60° with respect to the electric field. The change in the potential energy of the dipole is 1.0 J.

Explanation:

Δ U = pE(cos θ_{1 −} cos θ₂)

= 5 × 10⁻⁶ × 4 × 10⁵ (cos 0° − cos 60°)

= `2 xx (1 - 1/2)`

= `2 xx 1/2`

= 1 J