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Magnetic energy

Each magnetic field contains energy, also called magnetic energy. She is a constant in physics. Because a magnetic field is generated by electric currents, the magnetic energy is an energy form of moving charge carriers (electrons). To understand where this energy comes from, it's worth taking a look at how a magnetic field works.

How is a magnetic field generated?

Magnetism is described by magnetic fields. These are caused by magnetic materials (e.g., permanent magnets), electric currents (e.g., current-carrying coils), or a temporary change in the electric field. Magnetic field lines indicate the magnetic flux. As with the earth's magnetic field, magnets (e.g., bar magnets) have north and south poles, the former always aligning in the direction of the Arctic magnetic pole. Since work is done to generate a magnetic field, the field has energy in a magnetic energy store.

Depending on the material, the amount of magnetic energy may be different. The hysteresis describes this connection. Again, those effects are described by the Maxwell equations, which indicate why electrical charge carriers generate magnetic fields.

How can magnetic energy be calculated?

To describe the energy of a magnetic field (coil), a formula for magnetic energy can be set up. The unit of magnetic energy density at any point of a magnetic field in vacuum is(total energy: E) the following units and sizes are needed:

  • (magnetic field strength, CGS system: Oersted unit)
  • (magnetic flux density at point , unit Tesla)
  • L (inductance of the magnetic energy of a coil, unit Henry)
  • I (Amperage, Unit Ampere)
This results in:

Respectively. for the total energy:

The rule is: the higher the magnetic energy, the greater the magnetic forces.

Applications of magnetic energy

When a piece of iron is approximated to a magnet, an energy larger than that in the magnetic object is created in the air space in between. Depending on the permeability of the iron, the proportion of this energy decreases. But when the magnet and the iron touch each other, the field energy disappears completely in the airspace.

The magnet has to do some work for putting on, but it reduces its own magnetic energy. The interesting thing is that the magnetic field of the magnet is not destroyed, but is repositioned each time, when again external force has to be applied to separate the iron from the magnet. Then the magnetic energy in the running dream also increases again.

A classic example of the use of magnetic energy is the generator. Simply put, a magnet inside a coil is permanently rotated in a circle, with the magnetic field doing work. Here is the Lorentz force acting on moving electric charges in a magnetic field. As a result, current can be generated and a voltage can be induced when the magnetic field changes.