question_answer 98)

  Which of the following statements are correct? (a) Ferrimagnetic substances lose ferrimagnetism on heating and become paramagnetic (b) Ferrimagnetic substances do not lose ferrimagnetism on heating and remain            ferrimagnetic (c) Antiferromagnetic substances have domain structures similar to ferromagnetic substances and their magnetic moments are not cancelled by each other (d) In ferromagnetic substances, all the domains get oriented in the direction of magnetic field and remain as such even after removing magnetic field

Answer:

                  (a, d) Ferrimagnetic substances lose ferrimagnetism on heating and become paramagnetic. In ferrimagnetic substance domains are alligned in parallel and antiparallel direction in unequal numbers. In ferromagnetic substances, all the domains get oriented in the direction of magnetic field and remain as such even after removing magnetic field. Hence, (a) and (d) are correct choices.