Examples of Magnetism

We explain that what are examples of Magnetism? The Magnetism is the property of materials that are able to attract metallic objects, this due to a force field exerted by the same material.

The behavior of bar magnets is known to all who have taken a science course. The permanent magnets , which are usually made of substances containing iron , attract or repel other magnets. Also, by attracting other iron objects, they can be magnetized.

History of Magnetism

The phenomenon of magnetism was known to the Greeks since 800 BC. They discovered that certain stones, now called Magnetite, with the chemical formula Fe 3 O 4 , attracted pieces of iron. The legend assigns the name of magnetite in honor of Magnes shepherd, “the nails of his shoes and the cap (or tip) of his cane were strongly subjected to a magnetic field when he was herding his flock.

The poles of the magnet

In 1269, Pierre de Maricourt, using a steric natural magnet, made a map of the directions taken by a needle by placing it at various points on the surface of the sphere. He found that the directions formed lines that surrounded the sphere passing through two points diametrically opposite each other, which he called the poles of the magnet.

Subsequent experiments showed that any magnet , regardless of its shape, has two poles , called the North Pole and the South Pole , which have forces that act on each other in a manner analogous to electric charges. That is, like poles repel and different poles attract .

John Michell used the torsion balance to show that magnetic poles exert attractive and repulsive forces on each other, and that these forces vary as the inverse of the square of the separation distance.

Even though the force between two magnetic poles is similar to the force between two electric charges, there is an important difference. Electric charges can be isolated (which is manifested in the existence of the proton and the electron), while the magnetic poles cannot be separated .

That is, the magnetic poles are always in pairs . All attempts to detect an isolated pole have failed. No matter how many times a permanent magnet is divided, each piece will always have a north pole and a south pole.

Relationship between Magnetism and Electricity

The relationship between magnetism and electricity was discovered in 1819 when, in a class demonstration, Danish scientist Hans Oersted found that electric current flowing through a wire deflects the needle of a nearby compass.

A short time later, Ampere obtained the quantitative laws of the magnetic force between conductors carrying electric currents . He also suggested which orbits of electric current of molecular magnitude are responsible for all magnetic phenomena. This idea is the basis of the modern theory of magnetism.

Faraday and Henry found that an electric current could be produced in a circuit close to the first one. These observations show that a change in the magnetic field produces an electric field. Years later, theoretical work by Maxwell showed that a varying electric field gives rise to a magnetic field.

Properties of a Magnetic Field

The electric field E at a point in space has been defined as the force per unit charge acting on a test charge, placed at that point.

Similarly, the gravitational field g at a given point in space is the force of gravity per unit mass acting on a test mass.

The Magnetic Field vector B , sometimes called magnetic induction or magnetic flux density , at a given point in space in terms of the magnitude of the force that would be exerted on an appropriate test object.

The test object is a charged particle moving with velocity v. To facilitate its study, it is assumed that neither electric nor gravitational fields are present in the region of the charge.

Experiments on the motion of various charged particles moving in a magnetic field have provided the following information:

1.- The magnetic force is proportional to the charge q and the velocity v of the particle .

2.- The magnitude and direction of the magnetic force depends on the speed of the particle and the magnitude and direction of the magnetic field.

3.- When a particle moves in a direction parallel to the magnetic field vector, the magnetic force F on the charge is zero.

4.- When the speed makes an angle θ with the magnetic field B, the magnetic force acts in a direction perpendicular to both v and B; that is, F is perpendicular to the plane formed by v and B.

5.- The magnetic force on a positive charge has the opposite sense to the force that acts on a negative charge that moves in the same direction.

6.- If the velocity vector makes an angle θ with the magnetic field, the magnitude of the magnetic force is proportional to sin θ.

Based on the above, the magnetic force is written in the form:

F = qv * B

Magnetism Applications

The list of important technological applications of magnetism is very long. For example, large electromagnets are used to transport heavy bodies. Magnets are also used in measuring devices, transformers, motors, particle accelerators, and in horns.

Magnetic tapes are commonly used in sound recordings, TV recordings, and computer memories. Strong magnetic fields generated by superconducting magnets are used as a container medium for plasmas (heated to temperatures of the order of hundreds of millions of degrees Kelvin) used in nuclear reaction controller research.

Examples of Magnetism

Planet Earth has a magnetic field, the poles of which are declared the North Pole and the South Pole.

Magnetic fields generated by superconducting magnets are used as a container medium for plasmas.

Every magnet, natural or artificial, has two poles: North Pole and South Pole.

Magnetic tapes are commonly used in sound recordings, TV recordings, and computer memories.

Large electromagnets are used to transport heavy bodies.

Magnets are used in measuring devices

Magnets are used in the operation of motors.

Powerful magnets are used in the construction of the particle accelerators, to keep the particles isolated.

Magnets are used in the speakers, for better operation of the acoustic components.

Like poles repel each other (South Pole repels South Pole. North Pole repels North Pole).

Opposite poles attract each other (South Pole attracts North Pole. North Pole attracts South Pole).

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