There are some inventions which charged the human civilization. The first invention was the wheel, the second invention was electricity, the third invention was telecommunication, and the fourth invention was the computer. We will discuss here the basic introduction of electricity. Each substance in this universe is made of plenty of atoms and each atom has the same number of negative electrons and positive protons. As a result, we can say that each neutral substance has the same number of electrons and protons in it. The protons are immovable and strongly attached to the nucleus of the atoms. Electrons are also bounded to atoms and orbiting around the nucleus in different distinct levels. But some of the electrons can move freely or can come out from their orbit due to external influences. These free and as well as loosely bonded electrons cause electricity.
In neutral condition, the number of electrons and protons is the same in any piece of substance. But if somehow the number of electrons in a substance becomes more than the number of protons, the substance becomes negatively charged as the net charge of each electron is negative. If the number of electrons in a substance becomes less than the number of protons, the substance becomes positively charged.
The concentration of free electrons always tries to be uniform. This is the only reason for electricity. Let us explain in detail. If two dissimilarly charged conductive bodies come in contact, the electrons from the body of higher electron concentration will move to the body of lower electron concentration to balance the electron concentration of both bodies. This movement of charge (as electrons are charged particles) is electricity.
The related terms in electricity
- Electric Charge: As we told earlier that the number of electrons and number of protons are equal in a neutral body. The amount of negative charge and positive change is also equal in a neutral body since the electric charge of an electron and a proton is numerically equal but their polarity is opposite. But for any reason, the balance of the number of electrons and protons in a body gets distributed the body becomes electrically charged. If the number of electrons more than that of protons the body becomes negatively charged and the amount of charge depends on the number of excess electrons in the body. In the same manner, we can explain the positive change of a body. Here the number of electrons becomes lesser than that of protons. The positivity of the body depends on the difference between protons and electrons in the body.
- Electric Current: When charge flows from one point to another to make uniform charge distribution then the rate at which the charge is flowing called electric current. This rate mainly depends on the difference between the charged condition of two points and the conditions of the pathway through which the charge is flowing. The unit of electric current is Ampere and it is nothing but coulomb per second.
- Electric Potential: The level of charged condition of a body is known as electric potential. When a body is charged it gets the ability to do some work. Electric potential is the measurement of the ability of a charged body to do work. The current flowing through a conductor is directly proportional to the difference of electric potential between at two ends of the conductor. The electric potential can be visualized as the difference of water level in two water tanks linked with a pipeline. The speed of water flowing from the higher headed tank to lower headed tank depends on the level difference or head difference of the water in the tanks not on the quantity of water stored in the tanks. In the same way, the electric current between two bodies depends on the potential difference between two bodies not on the quantity of charge stored in the bodies.
- Electric Field: There is always a force between two nearly placed charged bodies. The force may be either attractive or repulsive depending on the nature of the charge of two bodies. When a charged body enters the nearby zone of another charged body the force is practically experienced. Space surrounds a charged body where another charged body can experience a force is called the electric field of the former body.
These above mentioned four terms are the main parameters of electricity.
How is Electricity Generated
There are three basic ways by which we generally produce electricity.
- Electromechanical Process: When a conductor moves in a magnetic field and the conductor cuts the field flux lines electricity is produced in the conductor. Depending on this principle all electrical generators work such as DC generators, alternators, and all kinds of dynamos.
- Electrochemical Process: In all types of battery electricity is produced due to chemical reactions. Here chemical energy gets converted to electrical energy.
- Solid State Electric Generation: This is the most modern process of electricity generation. Here, free electrons and holes are generated at a PN junction and distribution of charge carriers gets imbalanced across the PN junction when the junction is exposed in the light. These free electrons and holes and their imbalanced distribution across the junction cause electricity in an external circuit. On this principle, PV solar cells work.
Types of Electricity
- When electricity produced in the armature of a generator it is always alternating. That means polarity of electricity alters in a periodic interval. In DC generators the produced electricity in armature gets rectified through commutator. In alternators, the AC produced in the armature supplied to the external circuit through slip rings.
- When electricity does not change its direction it is called DC electricity. Batteries and solar cells produce DC electricity.
Generation Transmission and Distribution of Electricity
After electricity gets generated in an electrical power plant it gets stepped up by step up transformer for transmitting purpose. Generation of electricity at low voltage level is practical and economical. But low voltage transmission is not economical. But for electrical transmission, the generated electricity first gets stepped up and then after transmission it is stepped down by step down transformers for electrical distribution purpose. Generation of electricity, transmission of electricity and distribution of electricity are normally with three phase system. Very ultra high voltage ac transmission is not economical always and that is why dc transmission is sometimes used. The supply system of domestic houses may be a single phase AC but all commercial, industrial and bigger house supplies are of three phase system.