Basics of Electronics and electricity
Although we realize
the effects of electrical phenomena, many of them cannot be visualized. For
example, electric current cannot be seen, yet we can feel its effects, such as
electric shock, or see a light bulb light up, a motor running, etc.
Atomic theory is
used to satisfactorily explain the basic principles of electronics. Let's look
at some:
Matter: It's everything that
occupies a place in space, among the examples are, steel block, piece of wood.
Molecule: It is the smallest
portion of matter, which retains its properties, as an example the water
molecule (H2O)
Atom: It is the smallest
part of an elementary substance that has the properties of an element. All
substances are composed of grouped atoms.
In the atom there are two regions: the nucleus and the electrosphere. The nucleus is made up of two types of atomic particles: protons, which have a positive electrical charge, and neutrons, which have no electrical charge. In the electrosphere are located electrons, particles with a negative electrical charge, which rotate in elliptical orbits around the nucleus.
The negative charges
on electrons are attracted to the nucleus, which has a positive charge due to
the protons. This attraction compensates for the centrifugal force that tends
to pull electrons away from the nucleus. In this way, the electrons keep their movement
around the nucleus.
Normally, an atom
has the same number of protons and electrons and is therefore electrically neutral.
Electrons from the outermost layer of the electrosphere, the valence layer, are
attracted to the nucleus with lesser intensity. An external force can cause the
atom to lose or gain one or more electrons from that shell, becoming an ion.
An atom can have 1
to 8 electrons in the valence shell. Those that have up to 3 electrons in this
shell are more likely to lose electrons. Conductive materials are made up of
atoms of this type. In conductor atoms, the valence shell electrons move freely
between the atoms of the material, jumping from one atom to another in a
disorderly way. These are called free electrons. Due to their presence, these
materials easily allow the passage of an electrical current.
As an example of
conductors, we can mention metals such as copper, aluminum, gold, and some
ionic solutions, such as salts and acids.
Electric quantities
Magnetism: The principle that
keeps an atom's electrons rotating around the nucleus is magnetism, whereby
charges of the same sign repel and charges of the opposite sign attract.
Electricity: When a positively
charged and a negatively charged material are connected by an electrical
conductor, free electrons flow from the negatively charged material to the
positively charged one. This flow of electrons is called electricity. For a
long time it was thought that they actually flow in another way, it was too
late to change the publications that existed on electricity. Consequently, for
convenience, technical publications have made a commitment to assert that
electric current flows from the positive to the negative side, while electrons
flow from the negative to the positive side.
Electromagnetism: The term
electromagnetism applies to any magnetic phenomenon that takes place in an
electric current. When a conductor is traversed by an electric current, there
is an orientation in the movement of the particles in its interior. This
orientation of the movement of particles has an effect similar to the
orientation of molecular magnets. As a result of this orientation, a magnetic
field arises around the conductor.
Force Against
Electromotive: The counter-electromotive force is an electromotive force that is
contrary to or opposed to the main current flowing through a circuit. For
example, when the armature coils of an electric motor rotate, a
counter-electromotive force is generated in these coils by their interaction
with a magnetic field.
Electric tension: Called ΔV, also known as
potential difference (DDP) or voltage, it is the difference in electrical
potential between two points or the difference in potential electrical energy
per unit of electrical charge between two points. Its unit of measure is the
volt (named after the Italian physicist Alessandro Volta).
Electric current: It is the ordered
flow of particles carrying an electrical charge, or it is also the displacement
of charges inside a conductor, when there is a difference in electrical
potential between the ends. Such displacement seeks to re-establish the balance
that was disrupted by the action of an electric field or other means (chemical
reaction, friction, light, etc.).
Electrical
resistance: It is the ability of any body to resist the passage of electrical
current even when there is an applied potential difference. Its calculation is
given by the First Ohm's Law, and, according to the International System of
Units (SI), it is measured in ohms.
Electric power: It can be defined as
the work performed by the electrical current in a certain period of time. The
unit of measure of Power is the Watt; the ratio is defined as: P = U x I (Power
= Volts x Current).
Ohm's law
George Simon Ohm was
a German physicist who lived between 1789 and 1854 and experimentally verified
that there are resistors in which the variation of the electric current is
proportional to the variation of the potential difference (ddp). Simon carried out
numerous experiments with different types of conductors, applying various
voltages to them, however, he realized that in metals, mainly, the relationship
between the electric current and the potential difference was always constant. Thus,
he elaborated a mathematical relationship that says that the voltage applied to
the terminals of a conductor is proportional to the electric current that runs
through it, mathematically it is written as follows: V = Ri
Where:
V is the potential
difference, whose unit is the Volts (V);
I is the electric
current, whose unit is the Ampere (A);
R is the electrical
resistance, whose unit is the Ohm (Ω).
It is important to
note that this law is not always v it does not apply to all resistors, as it
depends on what constitutes the resistor. When it is obeyed, the resistor is ohmic
or linear. Simon's mathematical expression holds for all types of conductors,
both those that obey and those that do not obey Ohm's law. It is clear that the
conductor that complies with this law will always have the same resistance
value, regardless of the voltage value. And the driver who doesn't obeys, it
will have different resistance values for each voltage value applied to it.