Concept of Current 

Electric Current is best defined as the movement of charge over time. This means that Current (I) is determined by Change in Charge (dQ) divided by Change in Time (dT). Therefore, the basic unit of charge is 1 Ampere (A) or 1 C/s. It can be defined as the amount of positive charge that flows through a longitudinal cross section of a conductor in unit time. In short it is the rate of flow of electric charge in a conductor. Conventionally the direction of electric current is taken as the direction in which the positive charges move. So:

                                                              I = dQ/dt

The SI unit of current is the Ampere (A) and is defined as the current produced when positive charges flow through a conductor at the rate of 1Coloumb per second, where a Coloumb is the unit of electric charge.
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Quiz

The Ampere, the unit of current in an electric conductor, can be best expressed in terms of basic units as: 

 

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