Magnets are the materials or objects that produce the magnetic field where it is present. Magnetic fields attract or repel ferromagnetic materials like iron or other magnets. We come across magnets used in several ways like in the refrigerator, TVs, speakers, headset, laptop, the magnetic catcher in the door and many more. Magnets are powerful objects often used to lift heavy objects. Advanced devices like Magnetic Resonance Imagers (MRIs) use magnets to scan the internal parts of the body.
Stronger magnets like permanent magnets are made of a material that is magnetized and creates its own magnetic field. Rare earth magnets are the type of strong permanent magnets made of alloys of rare earth materials. The magnetic field produced by these magnets exceeds above 1.4 Tesla. These magnets are composed of the rare earth elements whose atomic numbers range from 57 and 71.
Know More About Rare Earth Magnets
These rare earth magnets are vulnerable to corrosion and are extremely brittle in nature. To protect from breaking and chipping coating and plating is done on the surface of the magnet. There are two types of rare earth magnets, namely, neodymium magnets and samarium–cobalt magnets.
Neodymium Magnets
These magnets were discovered in the year 1980. These magnets are composed of alloys like neodymium, iron, and boron. They are used in hard disk drives, electric motors for jewellery clasps, and magnetic hold-downs. Neodymium magnets are usually nickel-plated to protect from oxidation. Neodymium magnets are used in DC motors, servo motors, magnetic separators and in Medical devices.
Samarium Cobalt Magnets
These magnets are composed of primarily samarium, cobalt, and iron. It is tough to demagnetize samarium cobalt magnets since they have high operating temperatures and high resistance to corrosion. These magnets are coated to prevent oxidation. These magnets are used in Computer disc drives, sensors, linear actuators and satellite systems.
After learning the uses of rare earth magnets and its applications, let us understand about the Hall effect.
Let us imagine a situation where a material carrying current is placed in a magnetic field, perpendicular to the flow of current. Can you predict what happens?
There arises a difference in the voltage across an electrical conductor transverse to an electrical current in the conductor and to an applied magnetic field perpendicular to the direction of the current. This phenomenon was discovered in 1879 by the US Physicist Edwin Hall.
The electric field or Hall field which is created is a result of the force that the magnetic field exerts on the moving positive or negative particles which are present in the electric current. The Hall coefficient is defined as the ratio of the induced electric field to the product of the current density and the applied magnetic field. Hall effect is observed due to the nature of current in the conductor.
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