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  2. Displacement current - Wikipedia

    en.wikipedia.org/wiki/Displacement_current

    This polarization is the displacement current as it was originally conceived by Maxwell. Maxwell made no special treatment of the vacuum, treating it as a material medium. For Maxwell, the effect of P was simply to change the relative permittivity ε r in the relation D = ε 0 ε r E. The modern justification of displacement current is ...

  3. Maxwell's equations - Wikipedia

    en.wikipedia.org/wiki/Maxwell's_equations

    Maxwell's equations on a plaque on his statue in Edinburgh. Maxwell's equations, or Maxwell–Heaviside equations, are a set of coupled partial differential equations that, together with the Lorentz force law, form the foundation of classical electromagnetism, classical optics, electric and magnetic circuits.

  4. Electric displacement field - Wikipedia

    en.wikipedia.org/wiki/Electric_displacement_field

    In physics, the electric displacement field (denoted by D), also called electric flux density or electric induction, is a vector field that appears in Maxwell's equations. It accounts for the electromagnetic effects of polarization and that of an electric field , combining the two in an auxiliary field .

  5. Ampère's circuital law - Wikipedia

    en.wikipedia.org/wiki/Ampère's_circuital_law

    The displacement current is justified today because it serves several requirements of an electromagnetic theory: correct prediction of magnetic fields in regions where no free current flows; prediction of wave propagation of electromagnetic fields; and conservation of electric charge in cases where charge density is time-varying.

  6. Permittivity - Wikipedia

    en.wikipedia.org/wiki/Permittivity

    Permittivity as a function of frequency can take on real or complex values. In SI units, permittivity is measured in farads per meter (F/m or A 2 ·s 4 ·kg −1 ·m −3). The displacement field D is measured in units of coulombs per square meter (C/m 2), while the electric field E is measured in volts per meter (V/m).

  7. Gauss's law - Wikipedia

    en.wikipedia.org/wiki/Gauss's_law

    Using the "sifting property" of the Dirac delta function, we arrive at = (), which is the differential form of Gauss's law, as desired. Since Coulomb's law only applies to stationary charges, there is no reason to expect Gauss's law to hold for moving charges based on this derivation alone.

  8. Electromagnetic wave equation - Wikipedia

    en.wikipedia.org/wiki/Electromagnetic_wave_equation

    for virtually any well-behaved function g of dimensionless argument φ, where ω is the angular frequency (in radians per second), and k = (k x, k y, k z) is the wave vector (in radians per meter). Although the function g can be and often is a monochromatic sine wave , it does not have to be sinusoidal, or even periodic.

  9. Current density - Wikipedia

    en.wikipedia.org/wiki/Current_density

    In electromagnetism, current density is the amount of charge per unit time that flows through a unit area of a chosen cross section. [1] The current density vector is defined as a vector whose magnitude is the electric current per cross-sectional area at a given point in space, its direction being that of the motion of the positive charges at this point.