Electronics Engineering (ELEX) Board Practice Exam

What happens to the magnetization of a paramagnetic substance as the absolute temperature T is increased in a weak magnetic field?

1. Increases linearly with temperature

2. Decreases in proportion to 1/T

3. Remains constant

4. Increases exponentially with temperature

The correct answer is: Decreases in proportion to 1/T

In a paramagnetic substance, the alignment of magnetic dipoles is influenced by both temperature and the strength of the external magnetic field. As the absolute temperature (T) increases, the thermal energy causes greater random motion within the substance, which disrupts the alignment of the magnetic dipoles. The relationship between the magnetization and temperature for a paramagnetic material is described by Curie's law, which states that the magnetization is inversely proportional to the absolute temperature. Hence, as the temperature increases, the magnetization decreases in proportion to 1/T. This means that at higher temperatures, the paramagnetic materials exhibit a reduced degree of magnetization due to thermal agitation overpowering the effect of the external magnetic field. This behavior is characteristic of paramagnetic substances and highlights their dependence on temperature, displaying that the effective magnetization decreases as thermal energy disrupts the orderly alignment of magnetic moments.