3. UNIT II. ELECTRICITY
• Ohm´s Law.
• Cables and wires.
• Power and calculation of load center.
4. UNIT II. ELECTRICITY
TOPIC 1. OHM´S LAW
Electricity
Form of energy that manifests itself with the movement of
electrons in the outer layer of atoms on the surface of a
conductive material.
5. Electricity
• Static electricity.
It is produced in non-conductive materials. In these materials,
the induced electrical charge remains at rest; It does not move
because no current can flow.
Due to an unequal ratio between electrons and protons, a static
electrical voltage can be generated between the parts of this
insulating body.
UNIT II. ELECTRICITY
TOPIC 1. OHM´S LAW
6. Electricity
• Dynamic electricity.
When electrons are released from a substance and have to flow
into a material, it produces dynamic electricity.
In this type of electricity, electrons travel through an electrical
circuit made up of conductive materials.
UNIT II. ELECTRICITY
TOPIC 1. OHM´S LAW
7. Ohm's law is the relationship between electrical conductors and
their resistance that establishes that the current passing through
the conductors is proportional to the voltage applied to them.
The German physicist Georg Simon Ohm was the first to
experimentally demonstrate this relationship.
UNIT II. ELECTRICITY
TOPIC 1. OHM´S LAW
8. Statement
Ohm discovered in the early 19th century that the current through a metal was
directly proportional to the voltage or electrical potential difference across the
metal. The discovery of Ohm led to the idea of resistance in circuits.
Ohm's law expressed in equation form is V=RI, where V is the electrical
potential in volts, I is the current in amperes, and R is the resistance in ohms.
UNIT II. ELECTRICITY
TOPIC 1. OHM´S LAW
9. Key concepts of Ohm's law
Burden.
The source of all electrical charges lies in the atomic structure. The charge of
an electron is the basic unit of charge.
The measurement for charge is the coulomb (C) in honor of the French
physicist Charles Augustin de Coulomb. The charge of one electron is equal to
1.60 x10-19 C. This means that a charge of 1 C is equal to the charge of
6.25x1018 electrons.
UNIT II. ELECTRICITY
TOPIC 1. OHM´S LAW
10. Key concepts of Ohm's law
• Conductors
Those substances through which charges move easily are called conductors.
• Ohmic conductors
Ohmic conductors are those that comply with Ohm's law, that is, the resistance is
constant at a constant temperature and does not depend on the applied potential
difference.
• Non-Ohmic conductors
They are those conductors that do not follow Ohm's law, that is, the resistance
varies depending on the applied potential difference.
UNIT II. ELECTRICITY
TOPIC 1. OHM´S LAW
11. Key concepts of Ohm's law
Insulators
Those substances that resist the movement of charge are called insulators.
The valence electrons of insulators, such as water and wood, are strongly
restricted and cannot move freely through the substance.
Current
Electric current is the flow of charge through a conductor per unit of time. Electrical
current is measured in amperes (A). One ampere is equal to the flow of 1 coulomb per
second, that is, 1A= 1C/s.
UNIT II. ELECTRICITY
TOPIC 1. OHM´S LAW
12. Key concepts of Ohm's law
Types of current.
Direct Current (DC) or Continuos Current (DC)
It always circulates in only one direction, that is, from the negative to the
positive pole of the source that supplies it. This current always maintains its
polarity fixed.
UNIT II. ELECTRICITY
TOPIC 1. OHM´S LAW
13. Key concepts of Ohm's law
Types of current.
Alternating current (AC)
Alternating current differs from direct current in that it
changes its direction of circulation periodically and,
therefore, its polarity. This occurs as many times as the
frequency in hertz (Hz) of that current.
Alternating current is the type of current most used in
industry and it is also what we consume in our homes. The
alternating current for domestic and industrial use
changes its polarity or direction of circulation 50 or 60
times per second, depending on the country in question.
This is known as the frequency of alternating current.
UNIT II. ELECTRICITY
TOPIC 1. OHM´S LAW
14. Key concepts of Ohm's law
Voltage.
Electrical tension or potential difference (also called voltage) is a physical
quantity that quantifies the difference in electrical potential between two
points.
It can also be defined as the work per unit charge exerted by the electric field
on a charged particle to move it between two given positions.
Its unit is the volt (V).
UNIT II. ELECTRICITY
TOPIC 1. OHM´S LAW
15. Key concepts of Ohm's law
Electric resistance.
Electrical resistance is the difficulty with which electric charges flow through a
conductor.
Electrical resistance is related to the interaction of the conducting electrons as
they move from atom to atom along the conductor.
Resistance is measured in ohms or ohms, and is represented by the Greek
letter omega Ω.
UNIT II. ELECTRICITY
TOPIC 1. OHM´S LAW
16. Key points to remember
• Voltage moves current while resistance prevents it.
• Ohm's law refers to the relationship between voltage and current.
• Circuits or components that obey the V=IR relationship are known as ohmic
and present current-voltage graphs that are linear and pass through the
zero point.
• A mnemonic to remember Ohm's formula is to remember that “Long live the
Queen of England”; V=RI.
UNIT II. ELECTRICITY
TOPIC 1. OHM´S LAW
