Basics For EEE & ECE Students - 2

Q:- What is electrical potential ?

Whenever a piece of mass is lifted above the ground level, against gravity, some work is to be done. The quantity of work is done, due to this lifting, is the product of gravitational force on the mass and the height the mass has been lifted. This work done, is added in the potential energy of the mass.

Now think about an electrical charge which is entered in an electric field. As per nature of the charge, it will be attracted or repelled by the field. When the charge will move in the electric field, the work will be done against or by the electric force acting on the charge. So there must be some potential energy gained or lost due to this movement. Hence potential in an electric field is exactly the same as potential in the gravitational field.

So potential at any point in an electrical field, is the work done due to movement of a unit positive charge to that point from infinitely long distance.

The potential difference of two points in an electric field is defined as the net work to be done for moving one unit positive charge from lower potential to the higher potential point.

What is the unit of electrical potential difference?

If the unit of charge in the above definition is taken as one Coulomb and the work done, is one Joule for bringing this one Coulomb charge from one point to another, then the potential difference of these two points is considered as unity and it is denoted as one Volt.

If work done in bringing a positive charge of one coulomb from one point to another in an electric field is one joule, then the potential difference between the said points is considered as one Volt.
.
.
2Q:-  Proper definition of electric current?

Actually, before coming to the question that what is electric current, we need to know what is electricity. Now in some easier words, electricity can be defined as the movement of free electrons across any materials. The outer electrons of an atom is loosely attached with the nucleus, so not much energy is required to de touch this loosely bond electrons from the atom. So when the excitation is provided properly, this electrons get detached from the atom. As well as when these electrons collide with other loosely bond electrons, ultimately the no. of free electrons increases in the matter. And finally when this electrons flow from higher potential to lower potential, we can term that flow as electric current, which flows through the conductor. Now measurement of electric current is done on the basis of the charge of electrons because current is nothing but flow of electrons from higher potential to lower potential.

Now, as charge of an electron is = − 1.6021 × 10^{− 19} coulomb. So, the unit of electric current is expressed as coulomb/sec. Because, this term defines the no. of electrons flowing through a cross section of the conductor. Now coulomb/second is termed as Ampere(A). So the SI unit of electric current flow is Ampere(A).
.
.
Admin:- Sai Saikumar Jn ( Bellapuri saikumar)