# Formula: 2. Maxwell equation (differential form) Magnetic field

## Magnetic field

Magnetic flux density determines the magnitude and direction of the magnetic force on a moving electric charge.

## Divergence field

Scalar divergence field is the scalar product between the nabla operator $$\nabla$$ and the magnetic field $$\boldsymbol{B}$$: $\nabla \cdot \class{violet}{\boldsymbol{B}} ~=~ \frac{\partial \class{violet}{B_{\text x}}}{\partial x} + \frac{\partial \class{violet}{B_{\text y}}}{\partial y} + \frac{\partial \class{violet}{B_{\text z}}}{\partial z}$

The divergence field is no longer a vector field but a scalar function. The divergence field $$\nabla \cdot \class{violet}{\boldsymbol{B}(x,y,z)}$$ at the location $$(x,y,z)$$ is always zero. This means that there are no magnetic charges.

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