Energy Density of Electric and Magnetic Fields
Electric and magnetic fields store energy. In a vacuum, the (volumetric) energy density (in SI units) is given by
where E is the electric field and B is the magnetic field. The solution will be in Joules per cubic metre. In the context of magnetohydrodynamics, the physics of conductive fluids, the magnetic energy density behaves like an additional pressure that adds to the gas pressure of a plasma.
In normal (linear) substances, the energy density (in SI units) is
where D is the electric displacement field and H is the magnetizing field.
Read more about this topic: Energy Density
Famous quotes containing the words energy, electric, magnetic and/or fields:
“Because humans are not alone in exhibiting such behavior—bees stockpile royal jelly, birds feather their nests, mice shred paper—it’s possible that a pregnant woman who scrubs her house from floor to ceiling [just before her baby is born] is responding to a biological imperative . . . . Of course there are those who believe that . . . the burst of energy that propels a pregnant woman to clean her house is a perfectly natural response to their mother’s impending visit.”
—Mary Arrigo (20th century)
“Flabby, bald, lobotomized,
he drifted in a sheepish calm,
where no agonizing reappraisal
jarred his concentration of the electric chair—
hanging like an oasis in his air
of lost connections. . . .”
—Robert Lowell (1917–1977)
“We are in great haste to construct a magnetic telegraph from Maine to Texas; but Maine and Texas, it may be, have nothing important to communicate.”
—Henry David Thoreau (1817–1862)
“It matters little comparatively whether the fields fill the farmer’s barn. The true husbandman will cease from anxiety, as the squirrels manifest no concern whether the woods will bear chestnuts this year or not, and finish his labor with every day, relinquishing all claim to the produce of his fields, and sacrificing in his mind not only his first but his last fruits also.”
—Henry David Thoreau (1817–1862)