The torque acting on an electric dipole in a uniform electric field is maximum when the angle between ⃗p and ⃗E is _.

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(4) 90°. Idea: the torque on a dipole in a uniform field is τ = pE sin θ. sin θ is largest, equal to 1, at θ = 90°. Then τₘₐₓ = pE: the forces ± q⃗E are perpendicular to the dipole, so their lever arm is the whole length 2a. At 0° and 180° the torque is zero. So the torque is maximum at 90°.

The torque acting on an electric dipole in a uniform electric field is maximum when the angle between ⃗p and ⃗E is _______.

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