Question

What are magnetic keepers? Name its material.

Answer 1

Hint:As the name suggests, magnetic keepers are something which are used to protect and preserve the magnetization of materials. They are attached along both the poles of the magnets so that magnets do not react with the external fields and loose magnetization.

Complete answer:
The free poles of the magnets become weaker by time, repelling each other and interacting with other magnetic fields. Therefore, magnets need to be preserved and this is done by Magnetic keepers.

Magnetic keepers are used to preserve the strength of a magnet. They are made from magnetically soft iron or steel. Magnets having very low coercivity are preserved by these magnetic keepers. In ferromagnetic materials, the intensity of the acquired magnetic field that reduces the magnetization of the material is known as coercivity.

External fields can easily affect the domains of the magnets (that tend to point to a certain direction) that have low coercivities. For example, any nearby electric field or Earth’s magnetic field can also affect such magnets. On the other hand, super magnets which have high coercivities do not require a magnetic keeper. An external magnetic field cannot attract a magnet if it is protected by the magnetic keepers.

Note: Every magnet has a property called coercivity. It is the resistance of the magnetic material to the changes in magnetization. Magnets lose their coercivity even if they are not in use, because they tend to continuously interact with other magnetic fields or magnets. Alnico magnets are the magnets which have low coercivity. They are easily swayed by external magnetic fields, even the strength of a magnet can be lost easily by Earth’s magnetic field. Therefore, magnetic keepers are most important for them.