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Question
Find the amount of work done in rotating an electric dipole of dipole moment 3.2 x 10- 8Cm from its position of stable equilibrium to the position of unstable equilibrium in a uniform electric field if intensity 104 N/C.
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Solution
Given: p = 3.2 x 10- 8Cm, E = 104 N/C
To Find: Work done in rotating dipole (W)
Formula: W = pE (cos θ0 - cos θ)
Calculation:
At stable equilibrium, θ0 = 0°
At unstable equilibrium, θ = 180°
From formula,
W = pE (cos θ0 - cos θ)
= 3.2 × 10-8 × 104 (cos 0 - cos 180)
= 3.2 × 10-4 [1 - (-1)]
= 6.4 × 10-4 J
Work done in rotating an electric dipole is 6.4 × 10-4 J.
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