Search results
Results From The WOW.Com Content Network
In electrical engineering, impedance is the opposition to alternating current presented by the combined effect of resistance and reactance in a circuit. [1]Quantitatively, the impedance of a two-terminal circuit element is the ratio of the complex representation of the sinusoidal voltage between its terminals, to the complex representation of the current flowing through it. [2]
The impedance of free space (that is, the wave impedance of a plane wave in free space) is equal to the product of the vacuum permeability μ 0 and the speed of light in vacuum c 0. Before 2019, the values of both these constants were taken to be exact (they were given in the definitions of the ampere and the metre respectively), and the value ...
Electrostatics is a branch of physics that studies slow-moving or stationary electric charges. Since classical times , it has been known that some materials, such as amber , attract lightweight particles after rubbing .
In the equation, j is the imaginary unit, and ω is the angular frequency of the wave. Just as for electrical impedance, the impedance is a function of frequency. In the case of an ideal dielectric (where the conductivity is zero), the equation reduces to the real number =.
The above equations are the microscopic version of Maxwell's equations, expressing the electric and the magnetic fields in terms of the (possibly atomic-level) charges and currents present. This is sometimes called the "general" form, but the macroscopic version below is equally general, the difference being one of bookkeeping.
The electron was discovered in 1897 by J. J. Thomson, and it was quickly realized that it was the particle (charge carrier) that carried electric currents in electric circuits. In 1900, the first ( classical ) model of electrical conduction, the Drude model , was proposed by Paul Drude , which finally gave a scientific explanation for Ohm's law.
Coulomb's inverse-square law, or simply Coulomb's law, is an experimental law [1] of physics that calculates the amount of force between two electrically charged particles at rest. This electric force is conventionally called the electrostatic force or Coulomb force. [2]
D o and E o are the amplitudes of the displacement and electric fields, respectively, i is the imaginary unit, i 2 = − 1 . The response of a medium to static electric fields is described by the low-frequency limit of permittivity, also called the static permittivity ε s (also ε DC):