
	Where results make sense

Topic: Poynting theorem

Related Topics

Poynting flux

Poynting vector

Flux

Electromagnetic wave

Cross product

Microwave oven

John Henry Poynting

Lowell Liebermann

Routing

Packet

British Guiana

In the News (Tue 29 Dec 09)

Northern Trust

Marvin Harrison

Peter Chernin

Gary Locke

Match Play

Penelope Cruz

Mickey Rourke

AR Rahman

Danny Boyle

Hugh Jackman

	[No title]
		Poynting flux through surface denoted by dashed lines accounts for rate of change of electric energy stored in the enclosed volume.
		Poynting flux through this surface accounts for the rate of change of magnetic energy stored in the enclosed volume.
		The Poynting flux implied by (19) and (20) is
	web.mit.edu /6.013_book/www/chapter11/11.2.html (1485 words)

	Energy
		The primary source of the conservation of energy theorem has been, and will continue to be, the experimental impossibility of perpetual motion, an impossibility that must exist whatever our ideas may be on the portions of energy that the ether is obliged to supply in the absence of material bodies.
		Poynting's theorem, in demanding only the possibility of the transformation of an integral of volume (already partly arbitrary) to an integral of surface, expresses a lot less.
		Poynting's theorem expresses the law of energy only when we replace the fields with their representations based on retarded potentials, a restriction which removes a lot of its elegance and scope.
	www.datasync.com /~rsf1/crit/1908f.htm (1115 words)

	Poynting vector - Wikipedia, the free encyclopedia
		It points in the direction of energy flow and its magnitude is the power per unit area crossing a surface which is normal to it.
		For example, the Poynting vector near an ideally conducting wire is parallel to the wire axis - so electric energy is flowing in space outside of the wire.
		The Poynting vector becomes tilted toward wire for a resistive wire, indicating that energy flows from the e/m field into the wire, producing resistive Joule heating in the wire.
	en.wikipedia.org /wiki/Poynting_vector (402 words)

	Poynting vector probe for measuring electrical power - Patent 4810954
		The probe enables the direct measurement of electric power, in accordance with the Poynting theorem, by sensing the electric and magnetic fields associated with the high voltage and high current.
		In particular the present invention is directed to the ac power measurement wherein a Poynting vector is measured from the electric and magnetic fields generated in the space between coaxial conductors carrying the ac power.
		The method is based on the measurement of an alternative Poynting vector in the region between the surface of the iron core and the magnetizing winding.
	www.freepatentsonline.com /4810954.html (2304 words)

	Transmitting Antennas (Site not responding. Last check: 2007-10-11)
		I was interested in Dr K's idea that Poynting's theorem is a kind of inferior form of Gauss's theorem, that is not the case and indeed Gauss's theorem is used in the proof of Poynting's theorem.
		Dr K must have read Poynting's theorem at some stage and if he rereads it he will find that power enters the EM field via the term E.J, in other words electric current flowing against an impressed electric field...
		Going back to Poynting again, one thing he said in the introduction to his paper published in 1884 was that "if energy disappears at one point and reappears at another, it must be assumed that it has travelled through the intervening space".
	www.antennex.com /atheory3/_atheory3/00000002.htm (405 words)

	Kabbary, X-Field Antenna,US Patent 5,155,495
		The resulting electric and magnetic fields are cross-stressed in phase to synthesize the Poynting vector and produce radiated power within the small area surrounding the antenna.
		Thus due to the very small dimension of the whole antenna, the propagation delay across the interaction zones marked X and Y is negligible and so the correct simultaneity, orthogonality and rotationality exists and Poynting vector synthesis occurs and radio power radiates away with the velocity of light in the directions marked S.
		A widespread electric field E is created in arcs from the top plate to the lower plate and produces a cross-product with the magnetic field H rotating in the directions indicated and thus synthesises intense Poynting vectors S which radiate outwards in broad azimuthal angles to space.
	www.rexresearch.com /xfldant/xfldant.htm (5211 words)

	Radiofrequency Radiation dosimetry Handbook - Chapter 3.3 (Site not responding. Last check: 2007-10-11)
		Poynting's theorem is a powerful statement of energy conservation.
		Misapplying Poynting's theorem to field relations at a given point, or to only part of a closed surface instead of to an entire closed surface, can lead to serious misunderstanding of energy absorption characteristics.
		Poynting's theorem for time-averaged power and energy of steady-state sinusoidal E- and H-fields is of special interest.
	www.brooks.af.mil /AFRL/HED/hedr/reports/handbook/chp3-3-1.htm (3904 words)

	[No title]
		In addition, the figure, for simplicity, depicts the Poynting flux as associated with a time variable Alfven wave, but the Poynting flux could be associated with a steady state electric field structure with pairs of upward and downward field aligned currents producing the magnetic field perturbation (as illustrated in Mozer et al., 1980).
		We emphasize (as the principle experimental result of this paper) that during this pass (as was the case during the 5/9/97 pass), the intervals of strong earthward Poynting flux at Polar altitudes occur when the spacecraft is magnetically conjugate to regions of strong auroral energy flux as estimated by the UVI images.
		As expected from the structure of the electric fields, the Poynting flux is often confined to spatially localized layers in the plasmasheet boundary layer.
	ham.space.umn.edu /mike/wygantpaper/p_sub2.html (7469 words)

	Sir James Jeans - remarks on the Poynting vector. (Site not responding. Last check: 2007-10-11)
		For instance, if an electrified sphere is placed near to a bar magnet, this latter assumption would require a perpetual flow of energy at every point in the field except the special points at which the electric and magnetic lines of force are tangential to one another.
		The Poynting theorem actually is a relationship between the divergence (div S) of the Poynting vector flux S and the sources of energy at a point.
		For a region containing no sources or sinks of energy, the Poynting theorem merely states that div S = 0, and therefore by the divergence theorem, that the integral of the normal component of S over a closed surface surrounding a region containing no sources or sinks of energy must also be zero.
	www.ee.surrey.ac.uk /Personal/D.Jefferies/jjeans.html (312 words)

	The Poynting vector, power transmission, and the CFA.
		Yet there is a local elemental Poynting vector, which, if we interpret it as a local power flow, has no basis in the Physics of the situation.
		But once they are static, the Poynting theorem tells us that it is the divergence of the Poynting vector which is zero over any volume of space where the static fields exist, providing that there are no sources or sinks of energy inside the volume.
		Normally, for a capacitative load on the end of a transmission line, the power reflection coefficient is unity and the voltage at the terminals is in phase quadrature with the current.
	www.ee.surrey.ac.uk /Personal/D.Jefferies/poynting.html (3085 words)

	ENEE 380H Examination I October 1, 1998 (9:30 - 10:30)
		Find c) the instantaneous Poynting vector and the time averaged Poynting vector, d) the instantaneous field energy densities and the time averaged energy densities.
		Show that the Poyngting theorem holds for the system taking the cylindrical surface of radius a and height d around the capacitor and top and bottom plates as the closed surface.
		The magnitude of the time-average Poynting vector is
	www.ee.umd.edu /class/enee381-1.F2003/homeworks/381finsolf03.htm (220 words)

	[No title] (Site not responding. Last check: 2007-10-11)
		The time dependent theorem shows that three numbers are necessary to completely specify time varying power, and complex numbers supply but two; the third piece of information, a phase, is discarded when complex notation is formed.
		Omissions inherent to the complex Poynting theorem affect the calculated value of standing energy about an antenna, and hence the calculated value of Q. To avoid such omissions we develop a method of determining Q based upon the time dependent Poynting theorem that builds upon and extends our earlier work [Grimes and Grimes, 1997].
		The primary conclusion of this work is that the minimum possible Q of a radiation source established by Chu [Chu, 1948] does not extend to properly mixed and phased multimodal radiation fields.
	www.agu.org /pubs/abs/rs/1998RS900036/1998RS900036.html (226 words)

	Radio antenna - Patent 6025813
		The operation of the antennas disclosed in the prior-art referred to in the earlier patents have confirmed the Poynting Theorem as extended to apply to radio frequencies which requires that for radio wave generation, the electrical phase difference of the two fields must be exactly zero.
		The energy flow of the radio wave components E and H are seen to be synchronous and correctly rotated if the current on the conductor 2 is 90 degrees ahead of that of the current in conductor 1, and the current directions are as in FIG.
		The plane-wave view of the Poynting Vector is simplistic because it does not represent the inherent property of a radio wave system to enlarge, and fill space, as it travels outwards from its source as a spherical shaped wavefront.
	www.freepatentsonline.com /6025813.html (2284 words)

	[No title]
		Poynting theorem This theorem is the simple law of EM-wave energy conservation.
		Equation (2.13) is the integral Poynting theorem and equation (2.14) is its vector presentation.
		Then using Stokes’s theorem for the surface integral of a curl and using the same integration over surface S for both equations (2.13), we finally obtain after straightforward derivations and taking the limit EMBED Equation.3 (see Fig.
	www.ee.bgu.ac.il /~cee/emw/slides/lectures/lecture_2.DOC (1931 words)

	Serious inconsistencies in Beardens MEG and his other theories
		A classic is the ``Static Poynting Generator'' [6] proposed by Bearden, which is shown in Fig.
		Another claim of Bearden (found in the ``correspondence'' section of [5]) is that the energy travels and ``reaches beyond the solar system within a year of operation''.
		In this case he does not realize that the Poynting vectors are located only where the fields are, and that they do not travel around ``with the speed of light'' in any way.
	www.phact.org /e/z/bearden (1751 words)

	Re: Theory in Doubt (Site not responding. Last check: 2007-10-11)
		This is for the third time asking you to confirm the Gauss's theorem in complete, not The Poynting theorem, I am asking only about applying the present antenna theory,using A,V, or using any other developed antenna theory, on the Gauss's theorem to confirm its consistency, i.e.
		both sides of the theorem give the same resulting radiated power, not only one side as you have done.
		The divergence theorem has two sides, while the Poynting theorem is only representing one side of the divergence theorem, I,again ask you to prove that the other side of the Gauss's theorem is equal to the radiated power too from the antenna.
	www.antennex.com /atheory2/_atheory2/00000091.htm (137 words)

	[No title] (Site not responding. Last check: 2007-10-11)
		For systems in the sinusoidal steady state, a useful alternative to the form of Poynting's theorem introduced in Secs.
		The manipulations that are now used to obtain the desired "complex Poynting's theorem" parallel those used to derive the real, time-dependent form of Poynting's theorem in Sec.
		This information is equivalent to the time average of the (real form of) Poynting's theorem.
	web.mit.edu.cob-web.org:8888 /6.013_book/www/chapter12/12.5.html (1490 words)

	Electromagnetism: Maxwell's Equations and their Solutions - Numericana
		Another interesting consequence is that the field outside any distribution of charge with spherical symmetry has the same expression as the field which would be produced if the entire electrical charge was concentrated at the origin.
		This relation is due to a former student of Maxwell, John Henry Poynting (1852-1914).
		In the case of an electric dipole, the dominant far-field component of the Poynting vector is thus:
	home.att.net /~numericana/answer/maxwell.htm (3825 words)

	Crossed-Field AM Radio Transmission Antenna - 1/50 Wavelength Long; 100 kW
		From this beginning Hately and Kabbary report they were able to produce direct synthesis of the electromagnetic field using two large capacitor plates and two large cylinders of short length.
		The capacitor plates, called "D plates" for the term "D" in the Poynting theorem, were positioned parallel to one another to form a capacitor.
		The resulting electric and magnetic fields are cross–stressed in phase to synthesize the Poynting vector and produce radiated power within the small area surrounding the antenna.
	www.luminet.net /~wenonah/cfa (1194 words)

	Energy Citations Database (ECD) - - Document #136306
		The symmetry and the relations between the general Fresnel coefficients are investigated in the context of energy balance at the interface.
		In particular a new transfer matrix is introduced for energy fluxes in thin-film optics based on the Poynting and mixed Poynting vectors.
		Finally, the study of reciprocity relations leads to a generalization of a theorem of reversibility for conducting and dielectric media.
	www.osti.gov /energycitations/product.biblio.jsp?osti_id=136306&query_id=0 (284 words)

	The Poynting Flow Thruster v1.0
		When the +30kV DC High Voltage generator is switched on, the PFT v1.0 begins to set in motion and continues to turn continuously (see below, the video of the demonstration).
		an unbalanced flow of energy induced by an asymmetrical Poynting flow during the charging process in a flat capacitor.
		The resulting thrust shows that this principle can be used as a thruster in the vaccum space, this may open a new way in space propulsion...
	jnaudin.free.fr /html/pft01.htm (511 words)

	The Poynting Flow Thruster - Proof of concept
		During a charging process of a flat capacitor, the Poynting vector (S=ExH) comes from outside the capacitor towards the wire connections, parallel to the surface of the armatures inside the dielectric medium.
		A small neon light bulb has been connected in serie with the upper wire for showing the current flow during the charging process and the running phase (see the picture below).
		During the charging process, in a flat capacitor with the wires connected in the middle of the armatures,
	jnaudin.free.fr /html/pft12poc.htm (631 words)

	Conservation of energy (wave in a conductor)
		My best guess was to use Poynting's theorem in differential form, which says that the rate at which work is done per unit time per unit volume on the charges in the metal by the EM wave is given by
		This is the rate at which work is done on the charges in the metal per unit volume by the fields.
		Someone else from my class found a solution, but it is not the most general solution in that it does not show instantaneous conservation of energy but rather conservation in the mean.
	www.physicsforums.com /showthread.php?p=1097351 (1392 words)

	Poynting theorem - Definition, explanation
		The Poynting theorem is a statement due to John Henry Poynting about the conservation of energy for the electromagnetic field.
		where S is the Poynting vector representing the flow of energy, J is the current density and E is the electric field.
		Since the magnetic field does no work, the right hand side gives the total work done by the electromagnetic field.
	www.calsky.com /lexikon/en/txt/p/po/poynting_theorem.php (156 words)

	Amazon.com: "Stokes's Theorem": Key Phrase page (Site not responding. Last check: 2007-10-11)
		idea is needed in calculations related to the pullback of differential forms in Chapter 2, and is also relevant to Stokes's Theorem in Chapter 8.
		Green's Theorem (Stokes's Theorem for the plane) may be stated in terms of forms as follows.
		Using Stokes's Theorem, the above expression can be written as an integral over the line elements d.
	www.amazon.com /phrase/Stokes's-Theorem (484 words)

	Seminars at UAO (Site not responding. Last check: 2007-10-11)
		The findings suggests that SEE cannot be explained by simple coherent processes.
		An expression for the complex Poynting theorem is derived for the general fields.
		It is found that the complex Poynting theorem, in contrast to the Poynting theorem for real fields and sources, is not a conservation law of the imaginary part of electromagnetic energy.
	www.astro.uu.se /~seminar/abstracts/20050916.html (309 words)

	The Designer's Guide Community Forum - A Resource for Analog, RF, and Mixed-Signal Circuit Designers
		The equation you gave for Poynting's theorem assumed the use of phasors, which assumes sinusoidal signals.
		When using RMS you are allowing signals other than sinusoids to be used.
		Poynting's Therom: the changing E field only generates
	www.designers-guide.org /Forum/YaBB.pl?num=1103785899 (286 words)

	Spartanburg SC \| GoUpstate.com \| Spartanburg Herald-Journal
		John Henry Poynting (September 9,1852 – March 30,1914) was an English physicist.
		He was the developer and eponym of the Poynting vector, which describes the direction and magnitude of electromagnetic energy flow and is used in the Poynting theorem, a statement about energy conservation for electric and magnetic fields.
		Don't get the Herald-Journal delivered to your home?
	www.goupstate.com /apps/pbcs.dll/section?category=NEWS&template=wiki&text=John_Henry_Poynting (156 words)

Try your search on: Qwika (all wikis)