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Basic of Electricity and Fundamentals for SSC JE - Electrical Engineering

Basic of Electricity and Fundamentals - Electricity is is the physical phenomenon associated with the presence and flow of electric charge which determines electromagnetics interaction, so in order to understand electricity and flow of electric charge first we should understand set of atomic theory and then try to understand the behavior of the atom and it's constituent element electron protons and neutrons.


Everything which is around us and that posses mass and which can occupy some space then this is called matter. It has three state solid liquid and gas
these three states are defined as follows:-


A substance that has a definite shape, mass, and volume and which has resistance to change of its Shape and volume is called solid. Atoms in solid are tightly bonded with each other with a  force which is called interatomic force.   


It is a substance that has a definite mass but no definite shape. it takes the shape of the container in which it is poured. The inter-atomic forces of liquids are weaker than solid.


It is a substance that has a fixed mass but its volume and shape are not fixed. Gaseous atoms are bonded with weaker interatomic force as compared to liquid. and solid.


An atom is the defining structure of an element that cannot be broken by any chemical or physical process. An atom consists of a nucleus and this nucleus consists of protons and neutrons and electrons orbiting the nucleus.

 The structure of the atom is similar to the structure of the solar system where the sun is at the center and the other planets revolve around the sun, In the same way, the nucleus is at the center of the atom and the electrons revolve around the nucleus.


The nucleus is a  region inside the atom where the atomic fundamental particles like protons and neutrons reside. The nucleus was discovered by Ernest Rutherford. All the mass of an atom is present in the nucleus.


 Neutron is a subatomic particle. It is found inside the nucleus with the proton.it is an electrically neutral particle that means its net charge is zero.

Mass of neutron 1.67 ×10^-27 kg
Proton is also a subatomic particle .it is found inside the nucleus with the neutron.it is a positively Charged particle.
Mass of Proton= 1.`67 x 10^-27 kg
Charge of Proton=1.6 x10^-19 C


Electron is also a subatomic particle having a negative charge. electron revolving around the nucleus. Charges on both protons and electrons are equal in magnitude but opposite in sign and also an equal number of protons and electrons are found in an isolated atom. Due to an equal number of electrons and protons, the total charge on an atom is zero and due to this atoms always find in the neutral condition. 

Electrons revolve around the nucleus just like the motion of the earth. As we know the earth has two types of motion one is along its Orbit and the other is spinning around its axis and like this electron also a round nucleus as well as on its axis. On removal or addition of electrons from an atom, items require different types of property which are called charge.

Mass of electron=9.108 x10^-31 kg 
Charge on electron= -1.6 x 10^-19 C

Valence electron

a valence electron is those types of electrons that are found in the outermost shell of the atom. Valence electrons are responsible for the formation of the chemical bonds means electrons are responsible for bone formation.

Free electron

Metal has 1,2 or 3 electrons in the outermost shell. So it can easily lose the electron. These electrons are away from the nucleus and hence less attracted to the nucleus. these outermost shell electrons are called free electrons. these free electrons are responsible for the flow of electrical energy through any conducting material. 
Ion is a state of an atom in which the number of electrons and protons are not equal. In this Condition, the atom has some net effective charge. Either it may be positive or negative. If the atom has a net effective positive charge when it is called cation unless it is called an anion.


It is a process in which an atom becomes a cation or anion by the process of losing or gaining the electron. During this process either some amount of energy is gain or released by the atom this release or gain amount of energy is called ionization potential.

Some basic terminology used in  electricity

Electric current

The flow of charges through a given cross-section of a conductor is called current. Its SI unit is ampere and it is denoted by a capital letter of I.Direction of flowing of current is opposite to the flow of electron.

Types of current

a)  Alternating current

it is a current which varies continuously with respect to time. It may be of any type triangular wave, sine wave, cosine wave, etc.

b)  Direct current

the current which does not change with respect to time but remains constant with time is called direct current.

Effects of electric current

When current flows through a given conductor then it affects the surrounding and conductors. Out of all those effects, some major effects are discussed here

1) Heating effect:-when current flows through a given conductor then the internal resistance of metal resists the flow of the current of which produces heat energy and this phenomenon is called the heating effect of electric current.

2) Magnetic effect:- when an electric current is passed through a conductor then this current produce a magnetic field around this conductor and it has the capability to attract magnetic material, this effect is called the magnetic effect of electric current

3) chemical effect:- when an electric current is passed through a conducting liquid which is called electrolyte then it decomposed into its constituents and this effect is called the chemical effect of current

4)  Gas ionization effect:- when electric current flows through a discharge tube filled with mercury vapor, sodium vapor gas then this gas gets ionized. This effect is called the gas ionization effect of electric current.
The force required to flow the current in a conductor from one terminal to the other terminal is called electromotive force. it is generated by the cell or group of the cell. It is denoted by the capital letter E and measured in volt.


The force required to move a unit charge from infinity to a given point is called the potential of the charge at that point.it is measured in volt and its SI unit is volt. It is denoted by a capital letter of V.

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