Energy Density - Energy Density of Electric and Magnetic Fields

Energy Density of Electric and Magnetic Fields

Electric and magnetic fields store energy. In a vacuum, the (volumetric) energy density (in SI units) is given by

where E is the electric field and B is the magnetic field. The solution will be in Joules per cubic metre. In the context of magnetohydrodynamics, the physics of conductive fluids, the magnetic energy density behaves like an additional pressure that adds to the gas pressure of a plasma.

In normal (linear) substances, the energy density (in SI units) is

where D is the electric displacement field and H is the magnetizing field.

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