31 October 2018
- Last edited 31 October 2018
Excellent reference material and also excellent quotes/questions!
This is a real problem when an understanding is to be achieved! We see two issues:
- The Magnetic Field ( B ) and the Electric Field ( E ), are Orthogonal to each other and technically 90 degrees out of Phase. I show Current as E, with no Phase difference, and not Voltage for simplicity.
- It is not stated clearly, at any time, in most papers, which part of the Wave is a Standing Wave, Electric or Magnetic.
The answer is: Any wave form can be a Standing Wave! But for Energy "Generation" we MUST have opposing Magnetic Fields, thus creating a Standing Current Waveform, this, the Current Wave is at 90 degrees to the Magnetic Wave form:
I know you know all this, but for the other readers:
The Direction of the wave is in the direction of the Blue Arrow. The Wave Length is: λ = v / f - Where v is the speed of light in the medium one is using, and f is the Frequency.
Two Wave Forms, each in opposite Directions, shown by the Blue Arrows. In this case, equal in Amplitude. However we see the Current Waveform, depicted in Green as ( E ), has double the amplitude. This waveform is a Standing Wave, two Current Waveforms traveling in opposite Directions Summing.
The Wavelength for a standing wave is: 0.5 λ
Floyd Sweet told us:
If the directions of the two signals are such that opposite H-fields cancel and E-fields add, an apparently steady E-field will be created. The energy density of the fields remain as calculated above, but the value of the E-field will double from E/2 to E.
A very interesting description by Wikipedia:
In one dimension, two waves with the same wavelength and amplitude, traveling in opposite directions will interfere and produce a standing wave or stationary wave. For example, a wave traveling to the right along a taut string held stationary at its right end will reflect back in the other direction along the string, and the two waves will superpose to produce a standing wave. To create a standing wave, the two oppositely directed waves must have the same amplitude and frequency. The phenomenon can be demonstrated mathematically by deriving the equation for the sum of two oppositely moving waves.
Please forgive my inaccurate depiction, but the following is supposed to show two waves equal, but travelling in opposite directions, the Arrows in the Current Waveform are in the same direction:
However, the Arrows in the Magnetic Waveform are in opposite Directions!
Of course, the top and bottom waves in the above Image, when combined, create the wave below: A Standing Wave is the Current depicted in Green, which has double the Amplitude of each wave by itself.
So, the Current, because we know Standing Waves exist and we know how they are created, we know that this will Add, to create a Standing Wave.
Remembering, any wave can be made to be a Standing Wave, Magnetic, Water, Sound, light, hmm interesting...
We can build Noise Cancelling Headphones, but cant apply this Tech to Power?