Electric Current
When the same type of particles move in same direction, they form current.
Like water particles in river flow in one direction, forming water current.
Similarly, flow of air particles form air current.
Flow of electric charges in particular direction is called electric current.
Flow of electric charges can be understood by looking at structure of atom.
Atom has protons and neutrons in nucleus and electrons in different shells around it.
Electrons in the outermost shell are most loosely packed.
They get detached by absorbing thermal energy from outside.
These detachable electrons are free to flow and are called free electrons.
These free electrons start flowing in any direction. This results in zero net charge flow.
Zero net charge flow means zero current.
For current to flow, pressure difference is essential.
When we open mouth of balloon, air flows out due to pressure difference between air outside and inside balloon.
Similarly for electric current to flow, electric potential difference is essential.
Difference in electric potential between any two points is called electric potential difference.
Potential difference is also known as voltage. S.I. unit of electric potential difference is Volt denoted by V.
If there is potential difference present between two point, current will start flowing.
Electric current is net charge flowing through given area per unit time.
If we put this Mathematically,
So we can write,
Charges and Currents are measurable quantities and require units for measurement.
S.I. unit of charge is Coulomb denoted by C.
Since, current is charge per unit time, we can say
This 1 C/s current is also known as 1 Ampere denoted by A.
When 1 C of charge flows through particular area in 1 s, the current flow is said to be 1 Ampere.
So, S.I. unit of current is Ampere denoted by A. It is named after French Scientist, Andre-Marie Ampere.
Revision
Electric current is flow of electric charges through particular area per unit time.
Electrons in outermost shell of an atom can detach and are called free electrons.
For current to flow, free electrons should flow in particular direction.
Mathematically, electric current is given by:
S.I. unit of current is Ampere denoted by A.
The End