Magnetism is one aspect of the combined electromagnetic force. It refers to physical phenomena arising from the force caused by magnets, objects that produce fields that attract or repel other objects.
All materials experience magnetism, some more strongly than others. Permanent magnets, made from materials such as iron, experience the strongest effects, known as ferromagnetism. With rare exception, this is the only form of magnetism strong enough to be felt by people.
Opposites attract
Magnetic fields are generated by rotating electric charges, according to HyperPhysics. Electrons all have a property of angular momentum, or spin. Most electrons tend to form pairs in which one of them is “spin up” and the other is “spin down,” in accordance with the Pauli Exclusion Principle, which states that two electrons cannot occupy the same energy state at the same time. In this case, their magnetic fields are in opposite directions, so they cancel each other. However, some atoms contain one or more unpaired electrons whose spin can produce a directional Magnetic Field. The direction of their spin determines the direction of the magnetic field, according to the Non-Destructive Testing (NDT) Resource Center. When a significant majority of unpaired electrons are aligned with their spins in the same direction, they combine to produce a magnetic field that is strong enough to be felt on a macroscopic scale.
Magnetic field sources are dipolar, having a north and south magnetic pole. Opposite poles (N and S) attract, and like poles (N and N, or S and S) repel, according to Joseph Becker of San Jose State University. This creates a toroidal, or doughnut-shaped field, as the direction of the field propagates outward from the north pole and enters through the south pole.
The Earth itself is a giant magnet. The planet gets its magnetic field from circulating electric currents within the molten metallic core, according to HyperPhysics. A compass points north because the small magnetic needle in it is suspended so that it can spin freely inside its casing to align itself with the planet’s magnetic field. Paradoxically, what we call the Magnetic North Pole is actually a south magnetic pole because it attracts the north magnetic poles of compass needles.
magnet and its types
Magnets are objects that generate a magnetic field, a force-field that either pulls or repels certain materials, such as nickel and iron. Of course, not all magnets are composed of the same Elements, and thus can be broken down into categories based on their composition and source of magnetism. Permanent magnets are magnets retain their magnetism once magnetized. Temporary magnets are materials magnets that perform like permanent magnets when in the presence of a magnetic field, but lose magnetism when not in a magnetic field. Electromagnets are wound coils of wire that function as magnets when an electrical current is passed through. By adjusting the strength and direction of the current, the strength of the magnet is also altered.
Permanent Magnets
There are typically four categories of permanent magnets: neodymium iron boron (NdFeB), samarium cobalt (SmCo), alnico, and ceramic or ferrite magnets.
Neodymium Iron Boron (NdFeB): This type of magnet is composed of rare earth magnetic material, and has a high coercive force. They have an extremely high energy product range, up to 50 MGOe. Because of this high product energy level, they can usually be manufactured to be small and compact in size. However, NdFeB magnets have low mechanical strength, tend to be brittle, and low corrosion-resistance if left uncoated. If treated with gold, iron, or nickel plating, they can be used in many applications. They are very strong magnets and are difficult to demagnetize.
Samarium Cobalt (SmCo): Like NdFeB magnets, SmCo magnets are also very strong and difficult to demagnetize. They are also highly oxidation-resistant and temperature resistant, withstanding temperatures up to 300 degrees Celsius. Two different groups of SmCo magnets exist, divided based on their product energy range. The first series (Sm1Co5) has an energy product range of 15-22 MGOe. The second series (Sm2Co17) has a range that falls between 22 and 30 MGOe. However, they can be expensive and have low-mechanical strength.
Temporary Magnets
Temporary magnets can vary in composition, as they are essentially any material that behaves like a permanent magnet when in the presence of a magnetic field. Soft iron devices, such as paper clips, are often temporary magnets.
Electromagnets
Electromagnets are made by winding a wire into multiple loops around a core material—this formation is known as a solenoid. To magnetize electromagnets, an electrical current is passed through the solenoid to create a magnetic field. The field is strongest on the inside of the coil, and the strength of the field is proportionate to the number of loops and the strength of the current.
Artificial magnet
Magnets produced from magnetic materials are called artificial magnets. They can be made in avariety of shapes and sizes and are used extensively in electrical apparatus. Artificial magnets are generally made from special iron or steel alloys which are usually magnetized electrically. The material to be magnetized is inserted into a coil of insulated wire and a heavy flow of electrons is passed through the wire. Magnets can also he produced by stroking a magnetic material with magnetite, or with another artificial magnet. The forces causing magnetization are represented by magnetic lines of force, very similar in nature to the electrostatic lines of force.
Artificial magnets are usually classified as permanent or temporary, depending on their ability to retain their magneticproperties after the magnetizing forces have been removed. Magnets made from substances, such as hardened steel and certain alloys which retain a great deal of their magnetism, are called permanent magnets. These materials are relatively difficult to magnetize because of the opposition offered to the magnetic lines of force as the lines of force try to distribute themselves throughout the material. The opposition that amaterial offers to the magnetic lines of force is calledreluctance. All permanent magnets are produced from materialshaving a high reluctance.
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A magnetic field is a region of space where a magnetic force is exerted. The magnetic force is a force that attracts or repels other magnets. It is also the force that causes compass needles to point north.
The magnetic field is created by moving electric charges. The faster the charges move, the stronger the magnetic field. The magnetic field is also affected by the shape of the object that is creating the field. For example, a straight wire creates a magnetic field that is circular around the wire. A coil of wire creates a magnetic field that is concentrated in the center of the coil.
The magnetic field can be represented by magnetic field lines. Magnetic field lines are imaginary lines that show the direction of the magnetic force. The magnetic field lines always point from the north pole of a magnet to the south pole.
The magnetic flux is the amount of magnetic field passing through a surface. The magnetic flux density is the amount of magnetic field per unit area. The magnetic induction is the magnetic flux per unit volume.
The magnetic permeability is a measure of how easily a material can be magnetized. The magnetic susceptibility is a measure of how much a material is magnetized in a magnetic field.
Diamagnetism is a property of materials that are repelled by a magnetic field. Paramagnetism is a property of materials that are attracted to a magnetic field. Ferromagnetism is a property of materials that are strongly attracted to a magnetic field. Ferrimagnetism is a property of materials that are weakly attracted to a magnetic field. Antiferromagnetism is a property of materials that have no net magnetic field. Superparamagnetism is a property of materials that have a very small magnetic field.
Magnetostriction is the property of some materials to change their shape in a magnetic field. Magnetoresistance is the property of some materials to change their electrical resistance in a magnetic field. The Hall effect is the production of a voltage across an electrical conductor when a magnetic field is applied perpendicular to the current flow. The magnetocaloric effect is the change in temperature of a material in a magnetic field.
Magnetohydrodynamics is the study of the motion of a fluid in a magnetic field. Electromagnetism is the study of the interaction between Electricity and Magnetism. An electromagnet is a device that creates a magnetic field when an electric current is passed through it. A solenoid is a coil of wire that creates a magnetic field when an electric current is passed through it. A toroid is a donut-shaped coil of wire that creates a magnetic field when an electric current is passed through it.
Magnetic levitation is the ability of a magnet to float above a surface without touching it. Magnetic resonance imaging (MRI) is a medical imaging technique that uses magnetic fields to create detailed images of the inside of the body. Magnetic particle imaging (MPI) is a medical imaging technique that uses magnetic fields to create images of blood flow. Nuclear magnetic resonance (NMR) is a technique used to study the structure and properties of Molecules. Electron paramagnetic resonance (EPR) is a technique used to study the structure and properties of free radicals. Mössbauer spectroscopy is a technique used to study the structure and properties of materials at the atomic level.
Magnetoencephalography (MEG) is a technique used to measure the magnetic fields produced by the brain. Magnetocardiography (MCG) is a technique used to measure the magnetic fields produced by the heart. Magnetopneumography (MPNG) is a technique used to measure the magnetic fields produced by the lungs. Magnetogastrography (MGG) is a technique used to measure the magnetic fields produced by the stomach. Magnetooculography (MOG) is a technique used to measure the magnetic fields produced by the eyes. Magnetophosphene is a visual phenomenon that is caused by exposure to a magnetic field.
Magnetoception is the ability to sense magnetic fields. Magnetotactic bacteria are bacteria that can sense magnetic fields and use them to orient themselves. Magnetoreception in birds is the ability of birds to sense magnetic fields and use them to navigate. Magnetoreception in fish is the ability of fish to sense magnetic fields and use them to navigate. Magnetoreception in reptiles is the ability of reptiles to sense magnetic fields and use them to navigate. Magnetoreception in mammals is the ability of mammals to sense magnetic fields and use them to navigate. Magnetoreception in insects is the ability of insects to sense magnetic fields and use them to navigate. Magnetoreception in Plants is the ability of plants to sense magnetic fields and use them to orient themselves. Magnetoreception in Fungi is the ability of fungi to sense magnetic fields and use them to navigate.
What is a black hole?
A black hole is a place in space where gravity pulls so much that even Light can not get out. The gravity is so strong because matter has been squeezed into a tiny space. This can happen when a star is dying.
What is a neutron star?
A neutron star is a very small, very dense star. It is made up of neutrons, which are particles that are made up of protons and electrons. Neutron stars are formed when a star explodes in a supernova.
What is a white dwarf?
A white dwarf is a star that has used up all of its nuclear fuel. It is very small and very dense, and it is supported by electron degeneracy pressure.
What is a red giant?
A red giant is a star that is in the late stages of its life. It is very large and very bright, and it is supported by radiation pressure.
What is a brown dwarf?
A brown dwarf is a star that is not quite massive enough to sustain nuclear fusion in its core. It is larger than a planet, but smaller than a star.
What is a planet?
A planet is a large, round object that orbits a star. It is made up of rock, gas, or ice.
What is a comet?
A comet is a small, icy object that orbits the Sun. It has a long, thin tail that is made up of gas and dust.
What is an asteroid?
An asteroid is a small, rocky object that orbits the Sun. It is much smaller than a planet.
What is a meteoroid?
A meteoroid is a small piece of rock or Metal that orbits the Sun. It is much smaller than an asteroid.
What is a meteor?
A meteor is a meteoroid that enters Earth’s Atmosphere and burns up. It is also called a shooting star.
What is a meteorite?
A meteorite is a meteoroid that survives its passage through Earth’s atmosphere and hits the ground.
What is a comet nucleus?
The comet nucleus is the solid, icy body of a comet. It is made up of dust, ice, and small rocky particles.
What is a comet tail?
The comet tail is a long, thin stream of gas and dust that is left behind by a comet as it orbits the Sun. The tail is made up of material that is released from the comet nucleus when it is heated by the Sun.
What is a meteor shower?
A meteor shower is an astronomical event in which a number of meteors are observed to radiate, or originate, from one point in the night sky. These meteors are caused by streams of cosmic debris called meteoroids entering Earth’s atmosphere at extremely high speeds on parallel trajectories. Most meteors are smaller than a grain of sand, so they burn up and disintegrate before they can reach the ground.
What is a meteorite?
A meteorite is a solid piece of debris from an asteroid or comet that survives its passage through the atmosphere and hits the ground. Meteorites can be big or small, and they can be made of rock, metal, or a combination of both.
What is a solar flare?
A solar flare is a sudden, intense release of energy from the Sun’s surface. Flares are caused by the release of magnetic energy that has built up in the Sun’s atmosphere. They can cause radio blackouts on Earth and can even disrupt satellites in orbit.
What is a coronal mass ejection?
A coronal mass ejection (CME) is a large release of plasma and magnetic field from the Sun’s corona. CMEs can cause geomagnetic storms on Earth, which can disrupt power grids and satellites.
What is a sunspot?
A sunspot is a dark spot on the Sun’s surface. Sunspots are caused by concentrations of magnetic field that block the Sun’s light. They can be very large, and they can last for weeks or months.
What is a prominence?
A prominence is a large, loop-shaped cloud of plasma that is ejected from the Sun’s surface. Prominences are held in place by the Sun’s magnetic field. They can be very large, and they can last for days or weeks.
What is a filament?
A filament is a long, thin cloud of plasma that is suspended above the Sun’s surface. Filaments are made up of the same material as prominences, but they are much cooler. They can last for months or even years.
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Sure, here are some MCQs without mentioning the topic of magnetism:
A force that attracts or repels other objects of the same kind is called: (A) gravity (B) magnetism (C) electricity (D) friction
A material that is attracted to a magnet is called a: (A) ferromagnetic material (B) paramagnetic material (C) diamagnetic material (D) ferrimagnetic material
The north pole of a magnet will always point towards the: (A) south pole of another magnet (B) north pole of another magnet (C) equator of another magnet (D) center of another magnet
A compass is a device that uses a magnet to: (A) find direction (B) measure temperature (C) measure time (D) measure distance
The Earth is a giant magnet. The north pole of the Earth’s magnetic field is located near the: (A) north pole of the Earth’s geographic pole (B) south pole of the Earth’s geographic pole (C) equator of the Earth (D) center of the Earth
The Earth’s magnetic field protects us from: (A) solar radiation (B) cosmic radiation (C) both solar and cosmic radiation (D) neither solar nor cosmic radiation
The magnetic field of a bar magnet is strongest at: (A) the ends of the magnet (B) the center of the magnet (C) both the ends and the center of the magnet (D) neither the ends nor the center of the magnet
Two bar magnets will attract each other if: (A) the north poles of the magnets are facing each other (B) the south poles of the magnets are facing each other (C) the north pole of one magnet is facing the south pole of the other magnet (D) the south pole of one magnet is facing the north pole of the other magnet
A current-carrying wire will create a magnetic field around it. The direction of the magnetic field is given by: (A) the right-hand rule (B) the left-hand rule (C) the Fleming’s left-hand rule (D) the Fleming’s right-hand rule
A solenoid is a coil of wire that has a magnetic field. The strength of the magnetic field is proportional to: (A) the number of turns in the coil (B) the current flowing through the coil (C) the length of the coil (D) both the number of turns and the current flowing through the coil