A bar magnet having a magnetic moment of 2 $$ \times $$ 10⁴ J T^$$-$$1 is free to rotate in a horizontal plane. A horizontal magnetic field B = 6 $$ \times $$ 10^$$-$$4 T exists in the space. The work done in taking the magnet slowly from a direction parallel to the field to a direction 60^o from the field is

Curie temperature above which

A charged particle (charge q) is moving in a circle of radius R with uniform speed v. The associated magnetic moment $$\mu $$ is given by

Nickel shows ferromagnetic property at room temperature. If the temperature is increased beyond Curie temperature, then it will show