Examples

# Examples of Magnetic Energy

We explain that what are the examples of magnetic energy? The magnetic energy is inhabiting a permanent magnet or a conductor with electric current, and acts as forces that attract or repel the metal bodies . This energy is contained in the magnetic field , which is the space around the magnet or the conductor, and is the carrier of the aforementioned forces.

There are minerals such as magnetite Fe 3 O 4 , which have the property of attracting iron and other metals such as nickel and cobalt. This property is called magnetism, and the defining interaction is the magnetic force . This appears concentrated in certain parts of the material (it is not distributed evenly in it), where they are more intense, called magnetic poles .

## The magnets

Every magnetized body is called a magnet , and it is related to certain experimental facts:

• The magnetism is concentrated at its extremes and is reduced as we get closer to the center.
• Both extremes are different because, when there are no other forces, one always points to the north (and we name it the north pole N), and the other to the south of the Earth (and we name it the south pole S).
• When two equal poles face each other , there is a repulsive force between them .
• When two different poles face each other , there is a force of attraction between them .
• You cannot isolate a single north or south magnetic pole, or a particle that has a single pole.
• Electric and magnetic interaction are closely related and are only two different aspects of electric charge , a property of matter.
• The electrical and magnetic interactions must be considered together under the name of electromagnetic field .
• The magnetic field is not conservative, although the electromagnetic field as a whole is.

## Magnetic force

A charge q moving at a certain speed in a magnetic field experiences a so-called magnetic force . The magnetic force is the one exerted by the magnetic field on the charge, and it is proportional to the charge and its speed. The direction of the force is perpendicular to the velocity of the load. That is, if the load travels horizontally, the force will be vertical.

This force is called the Lorentz Force, and the equation to define it is:

F = qv Λ B

B is a vector whose modulus is the intensity of the magnetic field. This expression satisfies the experimental requirements as long as F is perpendicular to the plane formed by v and B (this depends only on the magnetic field applied in the experiment and on the point and therefore obtained experimentally), because otherwise the expression would never give the force that the particle feels.

B is the same at every point for all loads and speeds and it varies from point to point. It describes a characteristic property of the magnetic field, since it only depends on the coordinates and the body that creates the field.

The vector magnitude B is called magnetic field intensity , and sometimes magnetic induction . If we have a charge subjected to an electric field and a magnetic field (electromagnetic field), the force perceived by a particle of charge q is:

F = q [E + v Λ B]

Which represents the electromagnetic force , which is the sum of the electrostatic force plus the magnetic force.

## Work done by the magnetic field

The work done by a magnetic force F is defined by the equation:

dW = F * dl

where dl is the elementary displacement that has the same direction as v . Since the magnetic force is perpendicular to the displacement, we have dW = 0 . The magnetic force on a moving load changes the direction of the speed, two situations can occur:

• That the particle describes a circular path
• Let the particle describe a helix

## Examples of magnetic energy

1. When two magnets with equal poles approach, they repel each other.
2. When two magnets with opposite poles are brought together, they attract each other.
3. As an electric current flows through a conductor, a magnetic field is formed in it.
4. The magnetic field of a magnet alters the path of a charge passing near it.
5. By putting iron filings near a magnet, it will be attracted to the magnetic poles.
6. By bringing a magnet close to a ferrofluid, the ferrofluid will be attracted to completely envelop the magnet.
7. If small nickel bars are placed near a magnet, they will be attracted to the magnet.
8. If you put a magnet close to finely divided cobalt, the cobalt pieces will be attracted to envelop the magnet.
9. Magnetic energy is used in rotor motors: there is a fixed magnet, and when an electric current is induced in a winding that surrounds it, a magnetic field is produced opposite to its own, so the constant repulsion will make the magnets rotate .
10. Magnetic energy is naturally combined with electrical energy, which is why together they are called electromagnetic energy.

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