Magnetism is a force exerted by magnets when they attract or repel each other. Magnetism in physics is a phenomenon associated with magnetic fields that are produced due to the motion of electric charges. A Magnetic field is the area around the magnet where the magnetic force exists.
Every substance is made up of units called atoms. Each atom has electrons and particles that carry electric charges. The electrons spin around the core of the atom. This movement generates an electric current. Thus each electron acts like a microscopic magnet. In most of the substances equal number of electrons spin in opposite direction. Such substances are weakly magnetic. In other substances, most of the electrons spin in the same direction making the substance strongly magnetic.
Did you know: Metals such as iron, cobalt and nickel are attracted to magnets.
Properties of magnetism
The following are the properties of magnetism
- All magnets have two poles, a north pole and a south pole. Unlike poles attract each other and like poles repel each other.
- Magnetic strength is strongest at the poles.
- When you suspend a bar magnet horizontally, the magnetic field of the bar interacts with the magnetic field of the earth. This causes the bar magnet to come to rest in the north-south direction with the north pole of the magnet pointing towards the north pole of earth.
- The stronger the magnet the more will be the magnetic field produced by the magnet.
- The closer two magnets are, greater is the magnetic force between them.
Did you know: The Earth acts like a magnet with a North pole and a South pole. A collapsed star also called a neutron star has the strongest magnetic force compared to any other object in the universe.
Types of magnetism
Diamagnetism is generated in the presence of an external magnetic field. The external magnetic field results in the change of orbital motion of the electrons. The induced magnetism is very weak and is in an opposite direction to the applied field. Diamagnetism is found in elements with paired electrons.
Paramagnetism is usually observed in substances that have unpaired electrons. Such materials are weakly attracted by an external magnetic field and they form internal magnetic fields that are aligned in the direction of the applied external magnetic field.
Paramagnetism also happens in some metals due to the spin of the conducting electrons. Paramagnetic material can attract and repel like magnets when subjected to a magnetic field. When the externally applied magnetic field is increased these materials tend to get more magnetic. But the magnetism decreases with an increase in temperature. When the external applied field is removed these materials lose their magnetism.
It is a phenomenon in some materials in which there is bulk magnetic moment and magnetism is large. It is one of the strongest form of magnetism and forms the basis of all permanent magnets. The spin of the electrons of such materials is aligned in the presence of an external magnetic field.
Antiferromagnetism is a phenomenon in some materials where there is an antiparallel alignment of spins such that there is no net bulk magnetization. The spin of the electrons is aligned in a regular pattern with neighbouring electrons spinning in the opposite direction. This leads to overall no magnetization also called as antiferromagnetism.
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