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Magnet

Every person would have played with a magnet at least once in their life. The ability of these metals to stick to some metals and push away similar magnets has always fascinated everyone. However, magnets have a certain scientific aspect that is very important.

What is a Magnet?

A magnet is any piece of metal which when freely hung using a thread, comes to rest along the magnetic north-south direction of the earth. These pieces create a magnetic field around them, and they attract ferromagnetic substances. Similar poles of a magnet repel each other, and opposite poles attract each other.

We primarily divide magnets into natural magnets and man-made magnets. For example, some naturally found minerals due to the earth's magnetic field are magnetised and retain this magnetism for a long time. These are known as natural magnets. On the other hand, we use technology to make man-made or artificial magnets in industries or labs. Here magnetism can either be induced in a piece of metal by another magnet, or the metal piece can be magnetised using electricity.

Magnet Characteristics

A magnet has the following characteristics:

  • Dipole Property: If we divide any magnet into two parts, both parts will have their individual south and north poles. This property will hold true until the atomic level, where every magnet particle will have a magnetic dipole.
  • Property of Like-Pole Repulsion: Every magnet has a property by virtue of which the like poles repel each other and the unlike poles attract each other.
  • Directive Property: If we suspend any bar magnet in space, the magnet's poles will come to rest along the earth's magnetic north-south poles.
  • Attraction Property: The magnets have an attractive effect on the ferromagnetic materials, and the attraction is higher towards the poles.

Types of Magnet

There are three types of magnets. They include

  • Temporary magnets
  • Permanent magnets
  • Electromagnets

What are Temporary Magnets?

These are substances that become magnetic when they experience an external magnetic field. These include any piece of iron attached to a piece of magnet.

What are Permanent Magnets?

These are the magnets that do not lose their magnetic property once they are magnetised. There are huge applications of these magnets, and they hold importance in many processes.
The four common types of permanent magnets include:

  • Neodymium Iron Boron (NdFeB)
  • Alnico (aluminium, nickel and cobalt alloy)
  • Samarium Cobalt
  • Ferrite or ceramic (a combination of iron oxide in cobalt, nickel or strontium)

What are Electromagnets?

When an electric current passes through a coil around a soft iron core, the current produces a magnetic field that magnetises the soft iron core, displaying the characteristics of a magnet. However, there is a limitation on the magnetic property, and it lasts till the current passes through the coil. Furthermore, the strength of the magnetic field is also dependent upon the electric current.

Properties of a Magnet

Magnets have the following properties:

  • Magnets have magnetic field lines around them. There is a concentration of these magnetic field lines at the poles.
  • Every magnet has a dipole in each atomic particle.
  • Magnetic forces increase as the distance between the magnets or magnetic particles decreases.
  • The magnet will always come to rest in the north-south direction aligning itself along the earth's magnetic poles.
  • The magnets have an extension magnetism property. Any paper clip acts as a magnet till it is attached to a permanent magnet.

Reasons for Magnetism in Metals

The electrons in the metals have a spin which gives them a magnetic dipole. In normal situations, the spin orientation is such that the magnetic dipoles generated cancel each other out. However, when an electric field is applied, the electrons orient along a certain direction, providing a magnetic field.
Electric fields can produce magnetic fields and vice versa. This has been the principle for many electrical devices.

Applications of Magnets

Magnets have a lot of industrial, commercial, scientific and educational applications. Some of these are:

  • Magnets are an important component in Magnetic Resonance Imaging which has revolutionised the medical field.
  • Magnets play an important role in separating magnetic ore and from non-magnetic impurity, which is a crucial step in the concentration of ore in metallurgy.
  • In a recently discovered method, magnets help triple hydrogen production with the same amount of energy spent.
  • Magnets are an important component of devices like generators, motors, accelerators, and compasses.
  • They are indirectly useful in devices such as speakers and bells.
  • The superfast Bullet trains or the Maglev trains use permanent magnets and electromagnets to alleviate above the tracks and glide at superfast speeds.
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