Practicing Success
Which of the following substances can become a permanent magnet? |
Diamagnetic solid Paramagnetic solid Antiferromagnetic solid Ferromagnetic solid |
Ferromagnetic solid |
Ferromagnetism: A few substances like iron, cobalt, nickel, gadolinium and CrO2 are attracted very strongly by a magnetic field. Such substances are called ferromagnetic substances. Besides strong attractions, these substances can be permanently magnetized. In solid state, the metal ions of ferromagnetic substances are grouped together into small regions called domains. Thus, each domain acts as a tiny magnet. In an unmagnetized piece of a ferromagnetic substance the domains are randomly oriented, and their magnetic moments get cancelled. When the substance is placed in a magnetic field all the domains get oriented in the direction of the magnetic field and a strong magnetic effect is produced. This ordering of domains persists even when the magnetic field is removed, and the ferromagnetic substance becomes a permanent magnet. |