![]() Where dA is the area vector of the element, perpendicular to it The total current through the conductor is given as The direction of current density J is same as that of the electric field.įor each element of cross−section, the magnitude of current density J is equal to the current per unit area through that element. ![]() The direction of flow of positive charge is same as that of the direction of the electric field E, and the direction of flow of –ve charge is opposite to the direction of the electric field. To describe the flow of charge through a cross section of the conductor at a particular point, we use the term current density J. The SI unit of electric current is ampere. Instead, we choose current density (j), that is current flowing through unit area of the cross−section, as a vector quantity. ![]() The instantaneous current is given as I = dQ/dtĭirection of electric current as defined above will be taken along the direction of flow of positive charge (although in majority of conductors the charge carrier is electron which is negatively charged and hence electric current would be in a direction opposite to that of flow of electrons).ĭespite the direction that we associate with electric current, it is not a vector quantity. The current so defined above, is the average current over the period δt. For a given conductor AB, if 'δQ' charge flows through a cross-section of area A in time 'δt', then the electric current through the conductor AB, is given as ![]() Flow of electric charge constitutes electric current. ![]()
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