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:
“The preservation of life seems to be rather a slogan than a genuine goal of the anti-abortion forces; what they want is control. Control over behavior: power over women. Women in the anti-choice movement want to share in male power over women, and do so by denying their own womanhood, their own rights and responsibilities.”
—Ursula K. Le Guin (b. 1929)
“Those lumbering horses in the steady plough,
On the bare field—I wonder why, just now,
They seemed terrible, so wild and strange,
Like magic power on the stony grange.”
—Edwin Muir (1887–1959)
“O power of fantasy that steals our minds from things outside, to leave us unaware, although a thousand trumpets may blow loud—what stirs you if the senses show you nothing? Light stirs you, formed in Heaven, by itself, or by His will Who sends it down to us.”
—Dante Alighieri (1265–1321)