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A new fux density in electrodynamicsIn some of my last essays i asked about an experiment i have seen in TV in germany. A american group of scientists presentet the spinnimg of a black wheel while radiation incident perpendicurar on the wheel. The wheel was sensitively mounted in a evacuatet glass tube. It was around 1991 or 92. I do not know the origin, but i want to say that this was a great experiment. It leads to a flux density which is electromagnetic origin. Except the energy flux density there exists another flux density in electrodynamics, i call it spin flux density. It has the direction of the energy flux. It differs by a factor 1/frequency from the energy flux density and it is built up by the difference of the circular split of a elliptic polarized wave. Note the energy density is the sum (not the difference) of both. This simple formula i found 1992 cause i was concerned with polarization calculations. I found the following rules that time: 1. The energy is propotional to the square of the two main axes of the ellipse. while the spin flux is proportional to the product of both. 2. 2002 i found that this flux density fulfills a conservation law for the normal component when you have a incident wave on a non absorptive macroscopic medium. Formulas similar to the Fresnel formulas. The reflection coefficient for example is the square of the product of the reflection coefficients for the perpendicular and parallel polarized part of the incident wave. The transmission coefficient is the square of the product of the Fresnel transmission coefficients times a simple factor. Reflection plus transmission coefficient equal 1 for these spin fluxes. 3. Linear polarized waves do not transport spin. 4. The flux is proportiobal to the vector product of E and E*, the complex conjungated field. If you assume the electric field to be real, this flux would not exist, because the vector product of the same real vector is zero ! 5. Thermal light - circular or elliptic polararized - which comes directly from a thermal source like a lamp or the sun - does not show spinning of the wheel. This symmetry i call the spin symmetry of classical electrodynamics. There exists a variety of possibilities to form spinwaves from thermally emitted waves: 1. Using a circular polarizer to strip of one of the two rotating fields in a thermal emitted wave (the rotation for both goes in opposite direction) 2. Linear polarize thermal emitted wave and then make a metal or total reflecion (then you get light which is elliptic polarized and having spin 3. I also found a literature note that thin magnetic layers on a substrate could have such an effect. I also thought upon thermodynamic machines an found following rules 1. You can not find polarizers in nature with can polarize thermal light linear or circular with more than 50% efficiency. Normally very much less than 50 % efficiency. 2. Energy which is transferred in form of a momentum to the body (the rotating black wheel) can not be transformed to thermal energy at the same time. 3. There are frequency dependent effects which limit radiation machines to efficiencies not far away from the efficiencies of solar cells. Spin effects can be used to directly transform radiation energy to mechanical energy. Best regards [Only registered and activated users can see links. Click Here To Register...]Josef Matz Please excuse my english its not perfect. |

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