Given below are two statements:
Statement I: Susceptibilities of paramagnetic and ferromagnetic substances increase with decrease in temperature.
Statement II: Diamagnetism is a result of orbital motions of electrons developing magnetic moments opposite to the applied magnetic field.
Choose the correct answer from the options given below.
Answer: (A) Both Statement I and Statement II are true.
Statement I: for a paramagnet, Curie's law gives $\chi = \dfrac CT$; for a ferromagnet above its Curie temperature, $\chi = \dfrac{C}{T - T_C}$. In both cases $\chi$ increases as the temperature falls, so the statement is true.
Statement II: an applied field changes the orbital motion of electrons, producing induced magnetic moments opposite to the field. This is the origin of diamagnetism, so the statement is true.
Solution by Sreeraj P, M.Sc Physics