Electric current

Introduction :

Electric energy is essential ingredient for the industrial and all round development of any country. In these modern days the electricity become the necessary item for leading the daily life of human beings smoothly. All the industries of operations such as shipping, crushing, milling, punching are operated with the use of electrical motor and also some of the domestic appliances such as electrical iron, electrical heaters, grinders, mixers etc., needs electricity for this operations. Hence the electricity is very necessary for the developing of any country.

The utilisation of electrical energy as increased exponentially since first primitive network developed by the Thomas Alva Edison.

Electric current:

Current is a form of energy which flows electrical charge carriers like electrons.

drude and Lorentz, scientists after 19th century, proposed that conductors like metals containing a large number of free electrons while the positive ions are fixed in their locations. The arrangement of the positive ions is called lattice.

Understanding the behaviour of electrons in lattice Space.

Assume that a conductor is an open circuit.

The electrons moves randomly in lattice space of a conductor as shown in the figure 1. When the electrons are in random motion they can move in any direction.

Hence if you imagine any cross section as shown in figure the number of electrons crossing the cross section of a conductor from left to right in one second is equal to that of electrons passing the cross section from right to left in one second. It means  that net charge moving along a conductor through any cross section is zero when the conductor is in open circuit.

When the ends of the conductor are connected to the battery through a ball, the bulb glows because energy transform from battery to the bulb. The electrons are responsible for this transfer of energy. The electrons are responsible for transfer of energy from battery to bulb, they must have an order motion. When the electrons are in order motion there will be a net charge across through any cross-section of the conductor.This ordered motion of electrons is called electric charge.

potential difference:

              work done by the electric force on unit positive charge to move it through a distance from one end of the conductor to another end of the conductor is called potential difference.

Resistance:

          Resistance is the property of a substance which oppose the flow of current through it". Is called resistance.

Specific resistance:

           Speak resistance of a material is defined as the resistance offered between the opposite faces of a unit cube of that material is known as specific resistance.

EMF( electromotive force)

      The work done by the chemical force on unit negative charge to move it from positive terminal to negative terminal. This is called 

EMF( electromotive force)

.