Power
Dielectric heating must be distinguished from Joule heating of conductive media, which is caused by induced electric currents in the media. For dielectric heating, the generated power density per volume is given by
where is the angular frequency of the exciting radiation, is the imaginary part of the complex relative permittivity of the absorbing material, is the permittivity of free space and the electric field strength. The imaginary part of the (frequency-dependent) relative permittivity is a measure for the ability of a dielectric material to convert electromagnetic field energy into heat.
If the conductivity of the material is small, or the frequency is high, such that (with ), then dielectric heating is the dominant mechanism of loss of energy from the electromagnetic field into the medium.
Read more about this topic: Dielectric Heating
Famous quotes containing the word power:
“Rocked in the cradle of the deep
I lay me down in peace to sleep;
Secure I rest upon the wave,
For Thou, O Lord! hast power to save.”
—Emma Hart Willard (1787–1870)
“In Europe, charters of liberty have been granted by Power. In America ... charters of power [are] granted by liberty.”
—James Madison (1751–1836)
“True contentment is a thing as active as agriculture. It is the power of getting out of any situation all that there is in it. It is arduous and it is rare.”
—Gilbert Keith Chesterton (1874–1936)