39.An electric dipole is placed in a uniform electric field.The dipole when its axis is inclined to field direction at 30' experiences a torque 0.2N -m.If potential energy of the dipole when its axis is opposite to field direction is 0.4J then its potential energy. when its axis is along the field will be 1) -0.4J 2) -0.8J 3) 0.4J 4) zero