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Question
An electric dipole with dipole moment 4 × 10−9 C m is aligned at 30° with the direction of a uniform electric field of magnitude 5 × 104 N C−1. Calculate the magnitude of the torque acting on the dipole.
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Solution
Given: Electric dipole moment, p = 4 × 10−9 C m
Angle made by p with a uniform electric field, θ = 30°
Electric field, E = 5 × 104 N C−1
Formula: Torque acting on the dipole is given by the relation,
τ = pE sinθ
= `4 xx 10^-9 xx 5 xx 10^4 xx sin30`
= `20 xx 10^-5 xx 1/2`
= 10−4 N m
Therefore, the magnitude of the torque acting on the dipole is 10−4 N m.
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