Current Density

Definition - What does Current Density mean?

Current density or electric current density is related to electromagnetism and is defined as the amount of electric current flowing through a unit cross-sectional area. It is a vector quantity. The SI unit of electric current density is ampere per square meter. The symbol "J" is used for electric current density.

Corrosionpedia explains Current Density

Current density can be expressed by the formula:

J = I / A


J = Electric current density in amperes per sq. meter.

I = Electric current flowing through a given material or a conductor in amperes.

A = Cross-sectional area of a material or a conductor in square meters.

As an example, let us find the current density through a copper wire having a cross-sectional area of 4 square millimeters through which a 6 mA current is flowing. Using the formula J = I/A

Current I = 6 mA = 0.006 A

Area A = 4 sq. mm = 0.004 sq. m

J = I/A = 0.006 Amp / 0.004 sq. m = 1.5 Amp/sq. meter

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