An electric dipole with dipole moment 5×10⁻⁶ Cm is aligned with the direction of a uniform 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. 0.8 J 2. 1.0 J 3. 1.2 J 4. 1.5 J

Answer: 2. 1.0 J Key idea: potential energy of a dipole is U=-pEcosθ . Initially θ=0^° and then 60^° : Δ U=pE(cos0^°-cos60^°)=5×10⁻⁶×4×10⁵×1/2=2×1/2=1.0\ mathrm J

Topic: Electrostatic potential energy of charges and dipole· Electrostatics

An electric dipole with dipole moment 5×10^-6 Cm is aligned with the direction of a uniform electric field of magnitude 4×10^5 N/C. The dipole is then rotated through an angle of 60^° with respect to the electric field. The change in the potential en…

An electric dipole with dipole moment $5\times10^{-6}$ Cm is aligned with the direction of a uniform electric field of magnitude $4\times10^{5}$ N/C. The dipole is then rotated through an angle of $60^\circ$ with respect to the electric field. The change in the potential energy of the dipole is :

1. 0.8 J

2. 1.0 J

3. 1.2 J

4. 1.5 J

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Answer: 2. 1.0 J

Key idea: potential energy of a dipole is $U=-pE\cos\theta$.

Initially $\theta=0^\circ$ and then $60^\circ$:

$$\Delta U=pE(\cos0^\circ-\cos60^\circ)=5\times10^{-6}\times4\times10^{5}\times\frac12=2\times\frac12=1.0\ \mathrm J$$

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report

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An electric dipole with dipole moment 5×10^-6 Cm is aligned with the direction of a uniform electric field of magnitude 4×10^5 N/C. The dipole is then rotated through an angle of 60^° with respect to the electric field. The change in the potential en…

1 answer

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