An electric dipole of dipole moment P is placed parallel to a uniform electric field of intensity E. On rotating it through 180°, the amount of work done is .

Question

Accepted Answer

(1) 2PE. Given: dipole moment P, initially along ⃗E (θ₁ = 0°), turned to θ₂ = 180°. Idea: the work done in rotating a dipole equals the rise in its potential energy U = -PE cos θ: W = PE(cos θ₁ - cos θ₂). W = PE(cos 0° - cos 180°) = PE (1 - (-1)) W = 2PE The dipole moves from its most stable position (U = -PE) to its least stable one (U = +PE). So the work done is 2PE.

An electric dipole of dipole moment P is placed parallel to a uniform electric field of intensity E. On rotating it through 180°, the amount of work done is ______.

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