Is there a fractional frequency of light?

[Mustafa Bayram]

If emw spectrum is continuous, possible wavelengths should be infinite and there should be fraction of frequencies like 25,2 hertz. Well is there a fractional frequency of light?
In high school when we are teaching interference of light we say "only the same wavelength of lights interfere with each other because of that we are using a monochromatic light source". If the spectrum is infinite, the only way to have monochromatic light and see the interference pattern becomes lasers.

 

[.Scott]

There are fractional frequencies - any frequency is allowed.
Even with a laser, I could move the laser device towards you or away from you and the Doppler effect would finely adjust the frequency and wavelength.

As a matter of practicality, lasers are the way to produce interference patterns with light.

 

[f95toli]

If emw spectrum is continuous, possible wavelengths should be infinite and there should be fraction of frequencies like 25,2 hertz. Well is there a fractional frequency of light?
In high school when we are teaching interference of light we say "only the same wavelength of lights interfere with each other because of that we are using a monochromatic light source". If the spectrum is infinite, the only way to have monochromatic light and see the interference pattern becomes lasers.

There is no such thing as a perfectly monochromatic source: all sources send out light over a certain bandwith; this also includers lasers. That is, the spectrum of light contains "peaks" rather than "lines".,

 

[Nugatory]

there should be fraction of frequencies like 25,2 hertz

Sure. 25.2 hertz is 25200 kHz, or 25200000 megahertz…. and those numbers would look completely different if we reported the frequency in cycles per fortnight instead of cycles per second.

Exact non-fractional values and remarkable numerical correlations between otherwise unrelated quantities are most often artifacts of our choice of units, with no physical significance.

 

[Hyperfine]

25.2 hertz is 25200 kHz, or 25200000 megahertz ...

Misplaced decimal points?

 

[phinds]

Misplaced decimal points?

No, an example of how choice of units definitions affects numerical values.

 

[phinds]

correlations between otherwise unrelated quantities are most often artifacts of our choice of units, with no physical significance.

 

[Hyperfine]

No, an example of how choice of units definitions affects numerical values.

Then remove the word "is". As stated it equates 25.2 Hz with 25200 KHz. That is not a choice of units, it is simply an error.

 

[Nugatory]

Then remove the word "is". As stated it equates 25.2 Hz with 25200 KHz. That is not a choice of units, it is simply an error.

Of course it's an error - responding quickly while on the road. The general point about units is valid, the numbers are wrong.

 

[Hyperfine]

Of course it's an error - responding quickly while on the road. The general point about units is valid, the numbers are wrong.

Exactly. My concern was that distinction may well not be so obvious within a class B thread. Thus I pointed it out.