Question

A ferromagnetic substance becomes a permanent magnet when it is placed in a magnetic field because:
A. All the domains get oriented in the direction of a magnetic field
B. All the domains get oriented in the direction opposite to the direction of magnetic field
C. Domains get oriented randomly
D. Domains are not affected by magnetic field

Answer 1

Hint: Ferromagnetism is a phenomenon of acquiring the property of magnets by certain materials in presence of a magnetic field. Some materials such as Iron, Cobalt, nickel, etc are ferromagnetic materials.

Complete Step by Step Answer:
Let's understand how ferromagnetic materials acquire magnetism. The metal ions of ferromagnetic material are grouped and they are called domains. These domains behave like a small magnet. In a ferromagnetic substance, the orientations of domains are random. So, cancellations of their magnetic moments occur.

On placing the material in the magnetic field, the orientations of all the domains follow the direction of the magnetic field, resulting in a magnetic effect. On removing the magnetic field, the orientation of the domains remains unaffected. Therefore, the magnetic effect becomes permanent.
Therefore, statement A is right.

Additional Information:
Some properties possessed by ferromagnetic materials are:
1. Permanent magnetism is shown by these materials even after removing the magnetic field.
2. On heating these substances at high temperatures, they transform to paramagnetic.
3. In the liquid and gaseous phase, ferromagnetism is absent.

Note: There are different types of magnetism, namely, paramagnetism, diamagnetism, ferromagnetism etc. But the strongest form of magnetism is ferromagnetism. This magnetism is responsible for magnetism in magnets.