Concept of EMF and current

EMF is a short form of electromotive force. All the metals contain a large number of free electrons which move randomly in all the directions , inside the metal piece. The electrical force or pressure that causes the electrons to move in a particular direction is called as electromotive force. The units of E.M.F is Volts and EMF is also called as voltage or potential difference. It is denoted by V.

Electircal current is defined as movement of electrons or flow of electrons inside a conducting material. The unit is Ampera(A).The electron current flows from the negative end of the battery to the positive end.

Conventional current is said to be flowing from positive potential to a negative potential. The direction of flow of conventional current is always opposite to that of the electron current.

Relation between charge and current :

Current is defined as the flow of electrons.Higher the number of flowing electrons , higher is the value of current. But each electron carries a constant charge on it. Hence we can define the current as flow of charge per unit time or current is defined as the rate of change of charge with respect to time.

The relation between current and charge can be defined as following mathematical formula:

A current of one ampera is said to be flowing if a charge of one coulomb passes any given point in a conductor in one second. As each electron carries a charge of 1.6*10e(-19) coulomb , one coulomb charge corresponds to 6.25*10e18 electrons. When 6.25*10e18 electrons pass by a point in a conductor in one second , a current of one ampera is said to be flowing through the conductor.

In other words:
1 Ampera current corresponds to flow of 6.25*10e18 electrons.