Fundamentals of Electrical Circuits :Chapter 1

Relation between Charge and Current: 

The current is flow of electrons. Thus current can be measured by measuring how many electrons are passing through material per second. This can be expressed in terms of the charge carried by those electrons in the material per second. So the flow of charge per unit time is used to quantify an electric current.

                                                        I=Q/t Amperes                                                               (1)

Where,

                                                 I=Average Current flowing

                                                 Q=Total charge transferred

                                                  t= Time required for transfer of charge

Thus, Current can be defined as rate of flow of charge in an electric circuit OR in any medium in which charges are subjected to an external electric field.

Units: The unit for the current is Amperes.

Using Equation 1,

      

Current  =  charge/time  =  coulombs/sec  =  Amperes.