1. Introduction


This term came from the Greek word ELEKTRON which means Amber.

So the story begins from  the year 600BC, Thales Of Miletus(a Greek philosopher) observed the attraction of amber towards fiber and other small particles when rubbed vigorously.

Later around 1600 AD. William Gilbert also found that other substances besides amber , could also be electrified.

Benjamin Franklin was the first scientist who defined the positive charge.

So finally we came to know about the electricity

Electricity is the most versatile form of energy which can be prepared from a variety of sources and similarly it has various applications also.

And as we know it has a lot of importance in our day to day life from charging our mobile phones to making our trains move , from cleaning our clothes to baking our cakes, from controlling the temperatures to controlling the satellites

  • Electric charge

Whenever a loss or gain of electrons take place in a body , it is said to be charged .

lets understand the whole phenomenon with the help of atomic structure. an atom consists of protons and nutrons in the centre of atom and electrons revolving around the centre in a quantized or fixed space , the orbitals.

being persent on the outer side it is easy to transfer the electrons from one atom to another.

if the electrons and protons are present in an equal number the positive and negative charges nullify the effect of each other.

but if the electrons are more than the protons , there will be a net negative charge on the atom or substance. and similarly if the electrons are less than the protons there will be a net positive charge on the substance.

And it is clear from the above discussion that the charge is also a fundamental property just like Mass.

So the phenomenon which give the property to attract other objects is called electric charge, and the object is said to be charged or electrified.

Units of electric charge

The S.I. unit of charge is Coulomb represented by ‘C’.

And this is the amount of charge that is contained by 6 X  1018 electrons

Charge on 1 electron =  -1.6 X 10-19 C

Charge on 1 proton = +1.6 X 10-19 C

  • Electric current

To understand this concept in an easy way let read the following rhyme:-

Flow of Air

Makes  air current,

Flow of water

Makes water currents


Flow of electric charges

Make electric current.

Finally electric current is the amount of charge flowing through a particular area in a unit time.

Or simply it is the rate of flow of the electric charges.

It is represented by I

Electric current = charge/time

I = Q/t

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