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Frequency Of Visible Light?

01/05/2023 11:18 AM

OK we know light is a part of the Electromagnetic spectrum. Just like TV or Radio waves. It is just a MUCH higher Frequency. This is a two part question.

1- Say yellow visible light. my Googleing says is 516 terahertz. Am I correct?

What is the wavelength of such a frequency?

2-If you have a dish type of antenna say 10" in diameter. What is the gain in say db over a dipole at that frequency?

Yeah it is a 10" telescope.

I'm betting these numbers will be HUGE!

Joe

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#1

Re: Frequency Of Visible Light?

01/05/2023 11:45 AM
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#2
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Re: Frequency Of Visible Light?

01/05/2023 11:49 AM

Hi Eagle! YUP you confirmed that number for me. From what I got we matched.

Now the Gain of that telescope he he he

In terms of wavelengths, How many waves is 10" across?

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#3
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Re: Frequency Of Visible Light?

01/05/2023 12:27 PM

λ = c/f, where λ is wavelength, c = velocity of light, and f is frequency.

10 inch = 25.4 cm = .254m

Number of wavelengths = .254 / 581nm = 437,177.

" The angular resolution is proportional to the ratio of the wavelength, l, of the radiation divided by the telescope diameter: q = l/D."

https://jila.colorado.edu/~ajsh/courses/astr1120_03/text/chapter2/L2S4.htm#:~:text=The%20angular%20resolution%20is%20proportional,%3A%20q%20%3D%20l%2FD.

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#4
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Re: Frequency Of Visible Light?

01/05/2023 1:38 PM
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#5
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Re: Frequency Of Visible Light?

01/05/2023 2:01 PM

/ 580 = 437,931 or / 581 = 437,177

Sorry redshifted in all the excitement

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#6
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Re: Frequency Of Visible Light?

01/05/2023 2:04 PM

very cool! and BIG he he he in terms of how wide it is in wavelengths!

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#8
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Re: Frequency Of Visible Light?

01/05/2023 4:43 PM

I don't think there is any width or depth, it's an emanation, a beam of energy...the frequency and wavelength is just a 2 dimensional representation of a 3 dimensional phenomena...

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#9
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Re: Frequency Of Visible Light?

01/05/2023 8:07 PM

And you should be impressed that the mirror surface is typically ground and polished to an accuracy of λ/8 of a perfect paraboloid of revolution.

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#13
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Re: Frequency Of Visible Light?

01/06/2023 9:27 PM

It always amazes me that they can be that accurate!

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#7
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Re: Frequency Of Visible Light?

01/05/2023 2:43 PM

I think you mean blueshifted....there is no blue shift in this universe...well anyway your yellow may be red shifted from another frequency...if you're far away

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#11
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Re: Frequency Of Visible Light?

01/06/2023 2:23 PM

Ahhhh the Andromeda Galaxy…

The Andromeda Galaxy (M31) has a blueshift of about 186 miles per second (300 km/s). It is heading toward us and will merge with the Milky Way in about 4 billion years.

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#14
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Re: Frequency Of Visible Light?

01/08/2023 6:24 PM

Yes it's true that the yellow could be blueshifted...there are some examples beyond just the M31...

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#10

Re: Frequency Of Visible Light?

01/06/2023 7:11 AM

A1: To obtain wavelength from frequency, divide transmission speed by frequency. In the case of light, the transmission speed is the speed of light.

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#12

Re: Frequency Of Visible Light?

01/06/2023 3:16 PM

Radio is very interesting. At a wavelength of around 1 to .01 nm, a transition takes place. This area is called hard x-ray. Wavelengths smaller and frequencies higher are monopole emissions and wavelength above and frequencies below this point are dipole, tripole, quadpole or collective field emissions.

Monopole wavelengths go much smaller with much higher frequencies.

The monopole emissions come from rotation. The other emissions come from oscillations.

Frequency of oscillations can be varied by acceleration, gravity and other external influence and stimuli, like a torque.

We use oscillation to measure external influence with a 3 or 6 axis oscillation. This is how your smart phone knows it has been rotated 90 degrees. Unfortunately, we also use oscillation for our clocks. This gives error and a false apparent change in the rate of time. In which many conclude is evidence of spacetime.

It would be interesting to compare monopole emissions to the light emissions of these highly red shifted stars. The monopole emissions should not shift. Our clocks vary with height, just as a pendulum does.

But a vertical rotating shaft has the same time at both ends. We need a rotational time ticker to measure time accurately.

There are four accelerations and two stops in an oscillation. There are two constant accelerations in a rotation.

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#15
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Re: Frequency Of Visible Light?

01/13/2023 12:31 PM

Could we measure time more accurately using light from distant stars? The twisty-clock...

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#16
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Re: Frequency Of Visible Light?

01/13/2023 4:36 PM
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#17
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Re: Frequency Of Visible Light?

01/18/2023 10:21 AM

But the time will vary with the diameter,but referenced to a stationary point of observation,this will cancel out when observing the center of rotation.

Or not?

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#18

Re: Frequency Of Visible Light?

01/18/2023 10:28 AM

Here is a link that gives the relationship pf Frequency,wavelength and speed.

https://www.geeksforgeeks.org/difference-between-wavelength-and-frequency/

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#19
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Re: Frequency Of Visible Light?

01/18/2023 12:33 PM

I "like," near the beginning,where he used "interruption" when I think he meant "interpretation."

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#20

Re: Frequency Of Visible Light?

01/18/2023 4:09 PM

We can measure E and M wave fields on conductors and in circuits. They are easy to detect and display and easily seen as a wave function. A continuous changing and alternating wave, no doubt about it. We can also here them and with a proper transducer, we can even feel the waves. And we put a sine wave into a dipole and we receive a sine wave at the receiving dipole. It's only reasonable and logical that the propagation from one dipole to another.......is a sine wave function. Like between to circuit coils in circuits. That is a wave function. We assume the same for propagation.

But I don't think it is. I think the antenna fires, like an ignition coil. Only instead of collapsing back into the coil, the collapse is out into space. I believe a 1/2 period chunk of electrical disturbance is emitted every 1/2 period from the antenna. Giving the receiving antenna a 1/2 period duration of stimulus, this charges the RX antenna, and during the 1/2 period when the antenna is not being stimulated, the charged antenna discharges. The so called received "frequency" comes from detector, or antenna reactance. Our antennas and detectors, bounce electrically.

It does NOT take 1/2 period to emit that chunk. That chunk is emitted in a snap. It's an instant collapse or fire, but the emitted disturbance has a duration as it passes by.

This happens every 180 degrees of input to TX antenna.

The free change on the receiving antenna or a detector, is like a tank circuit......it rings when stimulated. And the whole dynamic is like a class B amp. The propagation is like the 1/2 period amp current, and the detection is the ringing, giving 360 degrees in the tank circuit.

The dipole has two modes of operation. On transmit, the dipole is sequentially end fed. The stimulus flows down the element and timing is important.

But in receiving mode, the antenna is charged broadside, NOT sequentially end fed, ALL of the antenna is being stimulated at the same time. Broadside fed.

These are two completely different types of current. And two completely different dynamics.

I believe that one photon can be emitted from a dipole. By feeding a precision 180 degree one shot into the TX antenna. And get one full 360 from the RX antenna.

A wave has a one full period of emission time. Like the time it takes for a speaker to move. And a wave has one full period of propagation passage. AND it takes one full period for detection. For a wave.

But a light strobe or EM emission strobe has an instant emission time, a 1/2 period passage propagation time.........and a full period detection time.

This instant emission character gives us a constant velocity, no matter what the emitter velocity is. The emitted wave is always at c speed before emission, no acceleration needed. The "emission" is actually and instant directional change, from angular to linear. The EM field has no inertia.....allowing that instant change.

The intermittent duty cycle of emission, explains all of our measurements with omnipresent time and length(space). As a matter of fact, the change in phase and frequency of a received emission, demonstrates and proves absolute time and length.

We just don't realize this yet.

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#21
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Re: Frequency Of Visible Light?

01/18/2023 4:36 PM

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#22

Re: Frequency Of Visible Light?

01/18/2023 4:47 PM

We shouldn't put our hubris on all living things. Only humans need a destiny.

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#23
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Re: Frequency Of Visible Light?

01/18/2023 5:42 PM

Why do you place yourself above other living things?

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#24

Re: Frequency Of Visible Light?

01/19/2023 12:20 PM

Since the difference between radio waves and visible light is given only by their frequencies/wavelengths, you can use the same formula to calculate the gain of a parabolic antenna and a parabolic mirror of a telescope (both relative to a λ/2 dipole). You can use the following site: https://www.everythingrf.com/rf-calculators/parabolic-reflector-antenna-gain and if you put your numbers you get a gain of 122dB, which is huge indeed. Also notice the very narrow beamwidth.

You can also see the formula used to calculate the gain:

However, the practical meaning is another story. Since you cannot get an electrical signal as you do with an RF frequency, it remains just a number. More interesting would be to have an RF parabolic antenna with the same gain. If you consider 516 MHz (a UHF frequency) everything will change a million times, so you will need a parabolic antenna of 100 km!! Quite impossible to build with our current technology.

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#25

Re: Frequency Of Visible Light?

01/22/2023 11:53 PM

instead of using the wave theory of light it might be possible to use the particle part of the wave, similar to solar cells.

also,

I am not sure of the size of nano particles for forming antenna arrays, but the semiconductor industry might have the ability to form reverse antennas down to the correct size at the bottom of etched out spaces, like wave guides. I do know experiments were done about 25 years ago to test the theory and wall profiles. I found out about the testing and was promptly told to mind my own business. They were using the steppers I worked on.

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#26
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Re: Frequency Of Visible Light?

01/23/2023 10:39 AM

Over 40 years ago,I saw an antenna design that consisted of a single solid triangle of metal,with a hole and conductors connected at one point of the triangle and the other at the hole.The book I saw it in is long lost and I cannot remember the title,but I can not find anything similar in antenna design today.Maybe it did not work well,or maybe too well?Has anyone else seen this design?

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#27
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Re: Frequency Of Visible Light?

01/23/2023 11:59 AM

I have seen long triangle shaped antennas.

I made my own tv antenna out of 12 copper triangles two grids of 6 triangles. one grid 90 degrees to the other. each grid connected at the sharp points. I think they were a little over 7 inches long and about three wide. on each grid the two outside triangles were connected to the opposite center triangle. I have to go back and find the note book to get the dimensions I used. It worked really well. I live in a different house now.

I figured out later, I could have used a bunch of about 15 inch pieces of copper wire bent to follow the outline and it would have worked just as good and been a lot less work.

I got the info to do this out of an AARL hand book.

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