Understanding Magnetism and Electromagnetism Principles
Magnetism
Materials likely to be attracted by a magnet are called ferromagnetic materials.
Types of Magnets
- Natural: (e.g., magnetite) have magnetic properties, but they are weak.
- Artificial
Permanent magnets retain their magnetic properties for a long time.
Temporary magnets only exhibit magnetic properties when subjected to a magnetic field.
Magnetic Field of a Magnet
It is the space in which magnetic phenomena are noticeable due to the magnet.
The magnetic field is more intense in some places than others, reaching its maximum intensity at the poles.
The chains formed from one pole to another are called lines of magnetic field strength.
If two magnets approach with like poles facing each other, they repel because the field lines confront each other. Otherwise, the lines are in the same direction and add up.
Electromagnetism
When a conductor is crossed by an electric current, a magnetic field appears around it, whose direction of the lines of force is determined by the right-hand rule.
The field strength depends on the intensity of the current.
- Field of a loop: It is very dispersed and weak. This can be improved by placing the conductor in a ring (loop).
- Field of a coil: The field of each turn adds to the next, focusing in the center.
In the extreme, two poles are formed.
The number of lines of force is called magnetic flux.
Magnetic induction indicates how intense the magnetic field is and depends on the number of turns of the coil. However, the longer the coil, the more dispersed the field lines become.
Magnetic permeability is the ability of a material to increase the lines of force of a magnetic field.
Magnetic Properties:
- Ferromagnetic: Concentrated lines of force, and its permeability is much greater than unity (hundreds or thousands of times).
- Paramagnetic: Permeability almost equal to unity, and the field lines that pass through it do not vary significantly.
- Diamagnetic: Permeability less than unity, and power lines running through them tend to be repelled.
Electricity and Magnetic Field
Introduction to Electromagnetism
Electromagnetic induction is the production of electricity by magnetic action. When moving an electrical conductor within a magnetic field, a driving force appears, shown as a voltage at the ends of the conductor.
This occurs whenever the field lines are cut.
Generation of Electricity
AC can be generated by rotating a coil oriented perpendicular to the rotating magnetic field within it.
Motors
When we introduce a conductor and pass current through it, it experiences a force perpendicular to the direction of magnetic flux, and its direction is determined by the left-hand rule:
- Index Finger: The direction of flow lines.
- Ring Finger: A sense of power.
- Thumb: Direction the cable moves.
Transformer
It transforms the voltage higher or lower, altering the parameters V and I, but without altering potency.
Energy is transferred through the varying magnetic field that appears in the transformer core.
The ideal transformer must meet the following equation: N1 / N2 = V1 / V2 = m (transformation ratio).
Also, as the power in the primary and the secondary is equal, we deduce that: V1 * I1 = V2 * I2
The Transformer in the Transport of Energy
To reduce losses, voltage increases during transport so that, for the same power, current intensities are lower.
In the place where energy is applied, the distribution is made to lower voltages and also adjust the voltage distribution to the various application cases.
The preference for AC over DC is that AC can be transformed easily.