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Post by buckleymanor1 on May 23, 2011 1:30:45 GMT 1
Well then why don't we see radio waves.Why won't the radio waves which enter our eyes slow down by the intraction of the material within our eyes to make them visable.
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Post by nickcosmosonde on May 23, 2011 3:19:12 GMT 1
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Post by buckleymanor1 on May 24, 2011 22:58:20 GMT 1
I don't understand why they should be the wrong frequency. So you would expect that radio waves entering the eye would slow down and shorten within the material and it's frequency would become lower making them visable. Maybe the frequency just don't get low enough.
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Post by speakertoanimals on May 25, 2011 18:05:59 GMT 1
The FREQUENCY would not change, just the speed and wavelength.
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Post by buckleymanor1 on May 25, 2011 22:32:40 GMT 1
The FREQUENCY would not change, just the speed and wavelength. Thanks, then I have missunderstood or this explanation is wrong from WIKI. en.wikipedia.org/wiki/FrequencyFrom than I get the impression that if one changes so does the other.
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Post by StuartG on May 25, 2011 23:00:14 GMT 1
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Post by buckleymanor1 on May 26, 2011 0:23:05 GMT 1
Cheers Stuart,the link I provided to WIKI don't work but yours does. It still states that . So I am still unclear as to why the frequency should remain the same as it clearly states it is proportional to the wavelength.
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Post by StuartG on May 26, 2011 0:48:58 GMT 1
Because it wavelength depends upon the medium the wave is travelling through. Remember the proviso ' in vacuo'. Have You ever tried to erect an antenna for a Short Wave Radio? If You erect the antenna one wavelength or half-wavelength You may well notice that the antenna has to be cut shorter than calculated. This is because the wire for the antenna has a velocity factor lower than 1. VR 1.0 is for the wave in vacuo, the antenna is in air and it made of metal with a VR less than 1. StuartG "proportional to the wavelength" i.e. in vacuo or 'in wire'! change the medium and the wave length changes. The frequency remains the same.
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Post by buckleymanor1 on May 26, 2011 8:39:01 GMT 1
Though the WIKI link does not make any proviso.It mentions that electromagnetic waves in a vacuum travel at the speed of light.Then goes on to mention that there waves are also inversely proportional to there frequency.No mention of in vacuo. Allthough the shortening of your aerial proves the contraction of the wavelength it does not show that frequency has not altered proportionally.
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Post by StuartG on May 26, 2011 10:37:11 GMT 1
"does not show that frequency has not altered proportionally." It does because the radio stays on station, and furthermore the signal is improved because the [now] tuned antenna resonates at the frequency, a better signal is heard and the signal strength meter shows improvement. So the the antenna resonates because the wavelength of it, is right, which improves the reception of the frequency [that hasn't changed]. "it does not show that frequency has not altered proportionally. "
"For periodic waves, and especially for sinusoidal waves, frequency has an inverse relationship to the concept of wavelength; simply, frequency is inversely proportional to wavelength λ (lambda). The frequency f is equal to the phase velocity v of the wave divided by the wavelength λ of the wave:
f = \frac{v}{\lambda}.
In the special case of electromagnetic waves moving through a vacuum, then v = c , where c is the speed of light in a vacuum and this expression becomes:
f = \frac{c}{\lambda}.
When waves from a monochrome source travel from one medium to another, their frequency remains exactly the same — only their wavelength and speed change." and to go back to a previous example of white light, there ain't no such thing really, white light is the 7 colours running together that we perceive as, what we call, white. So, where it says monochrome it means it [not black and white, as in the telly] a single colour. Cheers, StuartG
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Post by mak2 on May 26, 2011 10:46:14 GMT 1
"So I am still unclear as to why the frequency should remain the same as it clearly states it is proportional to the wavelength."
There is a proviso. Frequency is inversely proportional to wavelength, provided the velocity remains constant.
The formula is Frequency x Wavelength = Velocity
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Post by StuartG on May 26, 2011 11:02:14 GMT 1
Because they are talking from the standpoint of a particular set of circumstances, eg in vacuo light travelling freely in [say] space. When it travels through another medium, glass - my bit of antenna wire, then the speed in those is slower, 'c' ain't 'c' no more it is 'c' minus. Do You remember Kenny Everett with helium gas? Cheers, StuartG
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Post by speakertoanimals on May 26, 2011 13:18:47 GMT 1
Messing about with equations doesn't help, since it just says that frequency, wavelength and speed are all related.
WHY frequency remains constant is simple physics. It is that things have to stay in step at the interface.
Let's tale a simple example. I have a boring relay race, which starts with cars driven at a constant speed with one second intervals between them. Hence if the cars are all driven at fifty meters a second, then fifty meters is the analog of wavelength, and the frequency is one per second.
at a later part of the course, the car drivers hand their batons over to a succession of walkers, who then saunter off at one metre a second.
Now, it is OBVIOUS that the time interval between the walkers has to be the SAME as the time interval between the cars. The walker can't start until his baton arrives. Hence FREQUENCY is the same for both parts, one baton per second. The analog of the wavelength is less for the walkers, being one metre as opposed to fifty metres for the cars.
Think of the batons as the peaks (or troughs) of a wave, and the constant frequency just means that you can't have a peak travelling inside the material UNTIL a corresponding peak has arrived at the boundary outside. The rate at which peaks arrive at and leave the boundary have to be the same, hence FREQUENCY is constant, even though the speed and wavelength change depending on the material.
Anyone who claims they still don't understand had better just give up, frankly.......................
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Post by buckleymanor1 on May 26, 2011 15:01:04 GMT 1
I feel like giving up when there seems to be contradictions Speaks take your post 71.
So am I to conclude that white light before entering the prism is at one frequency. When in the prism and exiting it changes into different colours and corresponding different frequencies. Or does the frequency remain the same throughout. Remembering your previous comment what is it!
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Post by StuartG on May 26, 2011 16:06:13 GMT 1
No no 'white light before entering the prism is at one frequency' remember, the white light contains seven 7 visible colours [to us] en.wikipedia.org/wiki/Visible_spectrum, the prism 'breaks up' the perceived white light into its component parts. So white light is a 'fraud' remember? It's not a colour in itself, it's a combination, an homologation, a cadre of fellow travellers, multi-ethnic electromagnetic waves! StuartG
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