Question

An electric dipole of length 4 cm, when placed with its axis making an angle of 60° with a uniform electric field, experiences a torque of `4sqrt3`Nm. Calculate the potential energy of the dipole, if it has charge ±8 nC

Answer 1

Torque, τ=PEsinθ=(Ql)Esinθ    ...(1)

Here, l is the length of the dipole, Q is the charge and E is the electric field.

Potential energy, U=−PEcosθ=−(Ql)Ecosθ    ...(2)

Dividing (2) by (1):

`T/U=((Ql)Esintheta)/(-(Ql)Ecostheta)=-tantheta`

`=>U=-T/(tantheta)`

`=>U=-T/(tan60^@)`

`=>U=(-4sqrt3)/sqrt3`

⇒U=−4 J