Search results
Results From The WOW.Com Content Network
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).
The equation is a good approximation if d is small compared to the other dimensions of the plates so that the electric field in the capacitor area is uniform, and the so-called fringing field around the periphery provides only a small contribution to the capacitance. Combining the equation for capacitance with the above equation for the energy ...
These equations are inhomogeneous versions of the wave equation, with the terms on the right side of the equation serving as the source functions for the wave. As with any wave equation, these equations lead to two types of solution: advanced potentials (which are related to the configuration of the sources at future points in time), and ...
The relative permittivity (in older texts, dielectric constant) is the permittivity of a material expressed as a ratio with the electric permittivity of a vacuum. A dielectric is an insulating material, and the dielectric constant of an insulator measures the ability of the insulator to store electric energy in an electrical field.
Vacuum permittivity, commonly denoted ε 0 (pronounced "epsilon nought" or "epsilon zero"), is the value of the absolute dielectric permittivity of classical vacuum. It may also be referred to as the permittivity of free space , the electric constant , or the distributed capacitance of the vacuum.
The differential forms of these equations require that there is always an open neighbourhood around the point to which they are applied, otherwise the vector fields and H are not differentiable. In other words, the medium must be continuous[no need to be continuous][This paragraph need to be revised, the wrong concept of "continuous" need to be ...
where the permittivity = is the product of: ε 0, the permittivity of free space, or the electric constant; and; ε r, the relative permittivity of the dielectric. In the equation above, the use of ε accounts for the polarization (if any) of the dielectric material.
One useful example is that a centimetre of capacitance is the capacitance between a sphere of radius 1 cm in vacuum and infinity. Another surprising unit is measuring resistivity in units of seconds. A physical example is: Take a parallel-plate capacitor, which has a "leaky" dielectric with permittivity 1 but a finite resistivity. After ...