An electric dipole of length 1 cm is placed with the axis making an angle of 30° with an electric field of strength 104 N/C. If it experiences a torque of  102Nm. The potential energy of the dipole when it maks an angle 450 with the field is.

Torque acting at any position is  τ=pEsinθ  and potential energy at any position is U = -pEcosθHere in the first position  torque  τ= pEsin300 = 102  Potential energy at  450  =  U = -pE cos450Dividing we get τU= pE sin300pE cos 450   ⇒U = 10 2cos 450sin 300 =20 J