Mr. Scott
Under the Amazing One's Wing
- Joined
- Nov 23, 2005
- Messages
- 2,546
The, mathematically, it never falls to zero I would think.
-
Security incident: ISF was recently accessed by intruders. Please change your password, and change it anywhere else you used it. Read more
Engineer Creates "FREE ENERGY" Battery Charger
- Thread starter TheDoLittle
- Start date
The, mathematically, it never falls to zero I would think.
Ziggurat
Penultimate Amazing
- Joined
- Jun 19, 2003
- Messages
- 64,055
The thing is, any effect should have frequency dependence. If you're in the near-field limit, then that frequency dependence might be irrelevant for practical purposes: you can operate at close enough to a constant frequency for many cycles.
But it gets messier for very large distances. Imagine, for example, that we set up our receiver a light-minute away. We turn on our transmitter for ten seconds, then turn it off. None of the signal has even reached our receiver, so nothing happening at the receiver should have any effect. But in a truly steady-state case, we should expect some coupling between the two. How do we reconcile this? Well, in order to turn our receiver on and off, our signal can't be truly monochromatic. We've got to have a frequency window (which will actually be infinitely broad, if the signal is truly zero before and after). At some frequencies, the receiver should add to the load on the circuit. But at some frequencies, we might actually reduce the load on the circuit. So the sum, over all, could still go to zero for finite-duration signals, even if everything changes smoothly.
Mr. Scott
Under the Amazing One's Wing
- Joined
- Nov 23, 2005
- Messages
- 2,546
I had lunch with some real technical and physics wizards today and got some answers.
They knew of a case of a farmer who strung long lengths of barbed wire underneath high tension lines and got significant power off them, and when caught went to jail. It's stealing and loads the system.
I also asked about florescent tubes glowing beneath the power lines. They also load the system, but, depending on angle, can load it magnetically or electrically (like a transformer or a capacitor). In either case, it loads the system and is stealing.
At a distance, however, the wavelength complicates things. A coil that, for example, is beside a power company transformer that charges a battery, produces a "back EMF" that radiates back into the power company's transformer, reducing the power in the transformer and in the electrical grid.
With a radio transmitter, a receiver would load the transmitting antenna if it were less than one wavelength apart. The receiver would then transmit an opposing signal that would eventually arrive back at the transmitter, and its effect would depend on the phase relationship. The transmitter may even be turned off by the time the back EMF arrived, as pointed out above, making the transmitter, briefly, a receiving antenna for the incredibly feeble (by this time) reflection.
They knew of a case of a farmer who strung long lengths of barbed wire underneath high tension lines and got significant power off them, and when caught went to jail. It's stealing and loads the system.
I also asked about florescent tubes glowing beneath the power lines. They also load the system, but, depending on angle, can load it magnetically or electrically (like a transformer or a capacitor). In either case, it loads the system and is stealing.
At a distance, however, the wavelength complicates things. A coil that, for example, is beside a power company transformer that charges a battery, produces a "back EMF" that radiates back into the power company's transformer, reducing the power in the transformer and in the electrical grid.
With a radio transmitter, a receiver would load the transmitting antenna if it were less than one wavelength apart. The receiver would then transmit an opposing signal that would eventually arrive back at the transmitter, and its effect would depend on the phase relationship. The transmitter may even be turned off by the time the back EMF arrived, as pointed out above, making the transmitter, briefly, a receiving antenna for the incredibly feeble (by this time) reflection.
marting
Illuminator
- Joined
- Sep 18, 2003
- Messages
- 4,311
Need better wizards.
For power lines you are in near field for both E and B and can pretty much model things as such.
The B field component from power lines will not activate a fluorescent light no matter how close or what angle. OTOH, the E field component will without too much difficulty if the E field is parallel to the tube.
For power lines you are in near field for both E and B and can pretty much model things as such.
The B field component from power lines will not activate a fluorescent light no matter how close or what angle. OTOH, the E field component will without too much difficulty if the E field is parallel to the tube.