# Formula: Ohm's Law Electric Current Density    Electric field (E field)    Electrical Conductivity

## Electric Current Density

Unit
The electric current density is generally a three-dimensional vector and describes how much electric current traverses a given cross-sectional area: $$\class{red}{\boldsymbol j} ~=~ \begin{bmatrix} \class{red}{j_{1}} \\ \class{red}{j_{2}} \\ \class{red}{j_{3}} \end{bmatrix}$$

## Electric field (E field)

Unit
External electric field in which a conductive material is placed. This E-field generally has three components and it triggers an electric current: $$\class{purple}{\boldsymbol{E}} ~=~ \begin{bmatrix} \class{purple}{E_{1}} \\ \class{purple}{E_{2}} \\ \class{purple}{E_{3}} \end{bmatrix}$$

Unit

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