Question

What are permanent magnets? Give one example.

Answer 1

Hint: Magnets are materials or objects that produce a magnetic field. This magnetic field can be observed by putting this object in the field of any other magnet, this causes the magnets to attract or repel each other.

Step by step solution:
We know that the magnetic field is only produced by objects known as magnets, or by materials possessing enough magnetic energy to make a significant influence that can be observed by attracting ferromagnetic materials such as Iron towards it. So, when the influencing property of magnetic material does not reduce or diminish over time, the material is then known as a permanent magnet.
Now, let’s understand, how does a permanent magnet retain its magnetic property over time.
Magnetism is a property shown strongly by ferromagnetic materials which include elements iron, nickel and cobalt and some rare-earth materials as well. The domain theory explains the process of magnetization.
Inside any materials, magnetic fields are produced, which individually cancel themselves out due to their random orientation. However, a collective magnetic field can be produced by trying to align these domains using the influence of an electric or magnetic field. Electromagnets are produced using the influence of electric fields, however it is not a permanent process. Hence, as soon as the electric field is removed, the material again returns back to being non-magnetic.
But in some materials, which already have their domains arranged such that they point in the same direction, then even without any external influence these materials will produce a collective magnetic field. These are known as permanent magnets.
The main advantage of a permanent magnet is its ability to produce magnetic fields even in the absence of continuous supply of external energy as in the case of electromagnets.
Examples of permanent magnets include compass needles, which give us information about the earth’s magnetic field and the direction and speaker magnets, which are installed in speakers, earphones and headphones to generate sound.

Note: Sometimes, an iron nail which has been attached to a magnet for some time starts to attract other non-magnetic things such as iron fillings for a short span even after it has been detached from the magnet. This is because the domains of the iron nail had been reoriented. While this property does make it a magnet, however the magnetic effect of the iron nail is weak and is lost after some time. Therefore, an iron nail will not be considered as a permanent magnet.