Introduction to Magnets:
A magnet is a material that attracts other ferromagnetic substances towards itself due to its property of generating a magnetic field around it. This magnetic field though invisible has the power to attract another ferromagnetic object and another magnet if similar pole is approached. Only ferromagnetic materials are attracted and can be magnetized into new magnets.
Ferromagnetic materials can be divided into magnetically “soft” and “hard” materials. Examples of soft ones are annealed iron which can be magnetized very easily but tend to lose their magnetism early. On the other hand hard ferromagnetic materials such as alnico and ferrite when magnetized tend to retain their magnetism for a long time because of their alignment of their myocrystalline structure.
An electromagnet is made when current is passed through a coil of wire wrapped around a ferromagnetic material, but stops being a magnet when the current stops.
Physical properties of Magnets:
Every magnet has a magnetic moment. A magnetic moment or sometimes known as the magnetic dipole moment is a vector characterizing the overall properties of a magnet. In case of a common bar magnet the direction of its magnetic dipole moment point from its south pole to its north pole. The overall magnetic behavior varies widely according to the structure of the material particularly the magnet’s electronic configuration. Depending on the behaviors observed three different materials are seen.
Ferromagnetic materials which are strongly attracted to a magnet and the only type of materials that have the capacity to retain their magnetism for a long amount of time, for example lodestone. Paramagnetic materials are those whish are weakly attracted to a magnet, example platinum and aluminum. Diamagnetic materials on the other hand are repelled by both poles. Unlike the above two, they are even more weakly attracted by a magnet. For example, carbon, copper, plastic etc.
Uses and Safety with Magnets:
Computer monitors and televisions using cathode ray tubes employ electromagnets to form their displays. Speakers and microphones also use permanent magnets and a current carrying coil for converting the electrical energy in the wires into mechanical energy that creates the sound. Electric motors use a permanent magnet together with an electromagnet to convert electrical to mechanical energy mush like the speakers.
In medicine, magnetic resonance imaging is used to examine patient’s organs from outside. In the industry Electromagnetic separators are used to extract any metals from a mixture of organic and inorganic wastes.
Magnetism is involved in our day to day lives and is a wonderful phenomenon that benefits mankind in numerous ways.