Poynting-vektor
Dipol-stråling fra en oscillerende elektrisk dipol. Farven repræsenterer den elektriske feltstyrke, mens pilene repræsenterer Poynting-vektoren.
Poynting-vektoren () angiver størrelsen og retningen på energien transporteret i en elektromagnetisk bølge pr. areal og pr. tid. Vektoren er proportional med krydsproduktet mellem det elektriske felt og magnetfeltet :
hvor er vakuumpermeabiliteten.[1]
Vektoren er opkaldt efter John Henry Poynting, der først udledte den i 1884.[2] Oliver Heaviside udledte den senere uafhængigt af Poynting og tilføjede, at rotationen til et arbitrært vektorfelt kunne lægges til definitionen.[3]
Kildehenvisninger
- ^ Halliday, David; Krane, Kenneth S.; Resnick, Robert (2002). "38-6 Energy Transport and the Poynting Vector". Physics (engelsk). 2 (5. udgave). John Wiley & Sons, Inc. p. 870. ISBN 978-0-471-40194-0.
- ^ Stratton, Julius Adams (1941). Electromagnetic Theory (1st udgave). New York: McGraw-Hill. p. 132. ISBN 978-0-470-13153-4.
- ^ Nahin, Paul J. (2002). Oliver Heaviside: The Life, Work, and Times of an Electrical Genius of the Victorian Age. p. 131. ISBN 9780801869099.
 | Spire Denne artikel om fysik er en spire som bør udbygges. Du er velkommen til at hjælpe Wikipedia ved at udvide den. |
|
Medier brugt på denne side
VFPt Solenoid correct2.svg
Forfatter/Opretter: Geek3, Licens: CC BY-SA 3.0
Diagram of a solenoid and its magnetic field lines. The shape of all lines was computed according to the laws of electrodynamics.
Forfatter/Opretter: Geek3, Licens: CC BY-SA 3.0
Diagram of a solenoid and its magnetic field lines. The shape of all lines was computed according to the laws of electrodynamics.
Nuclear physics stub.svg
Nuclear physics
Nuclear physics
DipoleRadiation.gif
Forfatter/Opretter: MyName (Geoemyda (talk)), Licens: CC BY-SA 3.0
Electric Dipole Radiation, Dipole parallel to the z-axis, electric field and poynting-vector in the x-z-plane. Colours indicate the strength of the electric field vector , , red colours indicate , blue colours . The black arrows show . As E and S become very large in the center of the dipole they are limited to a certain value.
Forfatter/Opretter: MyName (Geoemyda (talk)), Licens: CC BY-SA 3.0
Electric Dipole Radiation, Dipole parallel to the z-axis, electric field and poynting-vector in the x-z-plane. Colours indicate the strength of the electric field vector , , red colours indicate , blue colours . The black arrows show . As E and S become very large in the center of the dipole they are limited to a certain value.
