Class 12th Physics 2017 Set3 Delhi Board Paper Solution
(i) Obtain the expression for the torque τ experienced by an electric dipole of dipole moment p in a uniform electric field, E.
(ii) What will happen, if the field were not uniform?
(i) Consider an electric dipole placed in a uniform electric field at an angle θ with the field.
The dipole will experience a torque.
So, the torque produced by two parallel forces qE acting as couple is equal to
τ = qE2 l sinθ
⇒ − q. E2l.sin θ = pE sin θ [p =q . 2l]
(ii) In case of non-uniform field, force acting on both the ends will not be equal. So, they will act as combination of couple and a net force. In this way, dipole will have both rotational as well as linear motion.
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