The origin of magnetism is explained by taking into consideration the circular motion of electrons. The electrons present inside the atoms move in circular orbits around the nucleus; this is similar to a circular coil carrying current. The electron’s orbital motion gives rise to the orbital magnetic moment.
The electrons tend to spin around in their own axis, thus creating a spin magnetic moment. The magnetic moment of an atom is the result of the vector sum of the orbital and spin magnetic moment. Based upon the magnetic properties, the magnetic substances are classified into three groups, namely diamagnetic, ferromagnetic, and paramagnetic.
Short Brief on Diamagnetic Substances
Diamagnetic Definition
Diamagnetic substances are magnetized weakly when placed in an external magnetic field in a direction that is opposite to the applied field. The type of magnetism that is exhibited by these substances is known as diamagnetism. Examples of diamagnetic substances are copper, gold, antimony, bismuth, silver, lead, silicon, mercury, etc.
The electron’s orbital motion gives rise to an orbital magnetic moment. In addition to this, the electrons tend to spin around their own axis, creating a spin magnetic moment. Electrons in an atom can have a clockwise or anticlockwise spin. In a similar way, the electrons can revolve around the nucleus in a clockwise or anticlockwise direction.
In the case of diamagnetic substances, the magnetic moments of atoms and the orbital magnetic moments have been oriented in such a manner that the vector sum of an atom’s magnetic moment becomes zero.
Characteristics
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In a diamagnetic substance, the magnetic moment of every atom is calculated to be zero.
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An external magnetic field can repel them weakly.
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If diamagnetic substances are placed in a non-uniform magnetic field, then the substances move towards the weaker side of the field from the stronger side.
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When these substances are placed in an external magnetic field, they get weakly magnetized in the direction that is opposite to the direction of the field.
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Magnetic susceptibility turns out to be negative in diamagnetic substances.
Ferromagnetic Substance
Substances that get magnetized strongly in an external magnetic field in a direction which is the same as the direction of the externally applied field are known as ferromagnetic substances. These types of substances retain their magnetic moment even after the removal of the magnetic field. Ferromagnetic substances tend to move from weaker to stronger parts of the external field. Some examples of ferromagnetic substances are iron, cobalt, and nickel.
In the ferromagnetic substances spin, magnetic moments have a large contribution. These substances consist of a large number of small units that are known as domains. These domains experience torque when a ferromagnetic substance is exposed to an external magnetic field. Due to this, the domains rotate and remain parallel to the direction of the field.
Characteristics
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A large number of small domains make ferromagnetic substances.
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These substances do not lose their magnetism when the external magnetic field is removed.
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These substances become paramagnetic when they are heated above the curie point.
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The external magnetic field strongly attracts ferromagnetic substances.
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These ferromagnetic materials tend to move from the weaker to the stronger part of the field when the magnetic field is non-uniform.
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If a rod of ferromagnetic substance is placed in a uniform magnetic field, the rod comes to rest with its length being parallel to the direction of the field.
Paramagnetic Substances
Substances that get magnetized weakly when placed in an external magnetic field in the same direction as the direction of the externally applied field are known as paramagnetic substances. These substances are different from ferromagnetic and diamagnetic substances. They have a tendency to move from the weaker to the stronger part of the magnetic field. Some examples of paramagnetic substances are calcium, lithium, tungsten, aluminum, platinum, etc.
In a paramagnetic substance, each atom has a permanent magnetic dipole moment because of the way they spin, the magnetic moments are oriented. However, the direction of magnetic moments can have random orientations when there is thermal motion. Due to which the net magnetic moment of this substance is zero.
Characteristics
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Every atom in this substance is considered as a magnetic dipole that has a resultant magnetic moment.
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The external magnetic field creates a weak attraction to these substances.
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They move from weaker to the stronger part of the field when placed in a non-uniform field.
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These substances lose their magnetism when the external magnetic field is removed.
Types of Magnets
The 3 types of magnets are-
Cause of Magnetic Field on Earth
The flow of liquid iron at the center of the Earth generates an electric current that produces magnetic fields. Earth’s magnetic field is produced very deep down in the core of the planet.
The cycle continues because the Charged metals passing through these fields produce their electric currents. This type of self-sustaining loop is called the geodynamo. The collective effect of magnetic fields produces 1 vast magnetic field going to the planet. This is the reason behind the magnetic fields on Earth.
Properties of a Magnet
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Magnetic poles always occur in pairs.
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The like poles of any magnet will repel each other while the unlike poles will always attract each other.
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The smaller the distance between 2 magnets, the greater magnetic force there exists between the 2 magnets.
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Whenever a magnet is left suspended freely in the air, it always eventually rests in a north-south direction.
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The pole that points towards the geographic north is called the North Pole of the magnet. The pole that points towards the geographic South is called the South Pole of the magnet.
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Magnets always attract ferromagnetic substances.
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It is noticeable that, when any magnet is submerged in some iron filings, the iron filings stick only to the end of that magnet. This happens because the magnetic attraction is maximum at the ends of any magnet. These ends are also called the magnet poles.
Conclusion
This article presents you with a clear picture of Diamagnetism, Ferromagnetism and Paramagnetism. You can check out for more information.