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electromagnetic induction
Induction of electromagnetique

Electromagnetic induction. The appearance of voltage in the conductor when it moves relative to a magnetic field. This induced electromagnetic field is greater when there is an increase in:

A) Relative movement between the carrier (for example, the coil) and the magnetic field.
b) The length of the conductor within the field (more turns in the coil).
C) The strength of the magnetic field.

Lenz's law says that the direction of the induced voltage is opposite to the direction of the current. See right-hand rules.

Voltage reading meter

Thus, it appears in the following drawing that a relatively fast movement gives a high voltage reading, while a relatively slow movement gives a low reading (but for a longer time).
Immobility gives a voltage equal to zero.

The production of voltage requires the flow of charge in the metal. This is what requires energy and the direction of the voltage and the direction of the charge flow (hence, as shown below when the south pole moves towards the coil. The same thing happens when the north pole moves in the opposite direction, and in both cases the direction of the current is given by a south pole at the left end of the coil and a north pole at its end The other. This reflects the change that caused it.

Electromagnetic induction forms the basis for many electrical machines, such as the generator, the transformer, eddy currents, and the back EMF, among the problems resulting from this effect. The bouncing electromagnetic field can counteract the motor effect, making motors less efficient.


electromagnetic waves
ondes fpl electromagnétiques

Electromagnetic waves are a field of radiations that differ in their wavelengths, but they all have the following properties:

* They all result from the movement of an electrical charge.
* It is transmitted by vibrating electric and magnetic fields.
* It passes through empty space at a speed of 300,000,000 meters/second, i.e. the speed of light.
* It is absorbed by matter when it moves inside it slowly.
* Like all waves, they show the effects of reflection, refraction, interference, and diffraction.
* The waves are transverse and show polarization effects.
* It can show the properties of a particle.

For practical reasons, the spectrum of electromagnetic waves is divided into a number of regions.

Region
Wave length (meters)
Frequency (Hz)

gamma gamma
- 10-12
-1021

X-ray
10-10-10-12
1021_ 1018

Ultraviolet
10-7-10-10
1018 -1015

visible light
10-6 -10-7
1015

Infrared
10-3-10-6
1015 -1012

microwave
10 -10-3-
1012-107

radio radio
106 -10
107 -10²

Note: All numbers here are approximate and the different wavelengths depend on the size of the source.


electromotive force (E)
(emf) force electromotrice

Electric motor force. Energy in an electrical source can move a charge to form a current. In any electrical source, there is a transfer of energy to this form. See cell and generator. The source also has resistance to the flow of charge through it, called internal resistance.

The electromotive force is often called voltage, which is the energy involved in transferring one coulomb of charge, and its unit is equal to the volt, the joule per coulomb.

There is an important extension of Ohm's law, which is the relationship (E = I (RT), and the diagram below defines the symbols used:

Circuit resistance R
Resistive electromotive force source
Stream
I = E / ( R + u )


electron
electron m


Electron. One of the fundamental particles of matter. Its mass is about two thousandths of the mass of a nucleon and it carries a negative charge. There are electrons in all natural atoms, and they form a cloud around the nucleus.

Electrons in metal act like gas particles. This electron gas gives metals their shiny surfaces and allows them to conduct heat and current well.
See also cathode rays and emission electron.