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An electric field of 1000 V/m is applied to an electric dipole at angle of 45°. The value of electric dipole moment is 10⁻²⁹ C·m. What is the potential energy of the electric dipole?

1. -7 × 10⁻²⁷ J
2. -9 × 10⁻²⁰ J
3. -10 × 10⁻²³ J
4. -20 × 10⁻¹⁸ J

Correct answer: -7 × 10⁻²⁷ J

Solution

Potential energy of a dipole is U = -pE cos(theta) = -(10^-29)(1000)(cos 45) = -7.07x10^-27 J, approximately -7x10^-27 J.

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