Question

Curie temperature is the temperature above which
A. Paramagnetic material becomes ferromagnetic material
B. Ferromagnetic material becomes diamagnetic material
C. Ferromagnetic material becomes paramagnetic material
D. Paramagnetic material becomes diamagnetic material

Answer 1

To solve the given question we must have the knowledge of the different types of materials that show different magnetic properties (paramagnetic, diamagnetic and ferromagnetic). We should also know what happens when these materials are heated.

Complete answer:
We know that a current carrying conductor shows magnetism. Meaning when we pass a current through a conductor, it produces magnetic field lines in the surrounding. Also, when we place the current conductor in an external magnetic field, the magnetic field exerts a force on the conductor.

Other than a current carrying conductor, some materials show magnetic properties. These materials show the magnetic properties due the motion of the electrons inside them. One of those materials is paramagnetic materials. Paramagnetic materials are those materials that are weakly attracted by an external magnetic field. When these materials are placed in an external magnetic field, they are weakly magnetised in the direction of the magnetic field.

Ferromagnetic materials are those materials that are strongly attracted by an external magnetic field. When these materials are placed in an external magnetic field, they get strongly magnetised in the direction of the magnetic field. The magnetising effect remains even after removing the external magnetic field.

However, when ferromagnetic materials are heated, they lose their properties and are converted into paramagnetic materials above a certain temperature. This temperature is called Curie temperature. Therefore, Curie temperature is the temperature above which ferromagnetic material becomes paramagnetic material.

Hence,the correct option is C.

Note: Paramagnetic materials are those materials that are weakly repelled by an external magnetic field. When these materials are placed in an external magnetic field, they are weakly magnetised in the direction opposite to that of the magnetic field.Since the magnetising effect on the ferromagnetic materials remains even after removing the external magnetic field, they are used as permanent magnets.