Relation between photons and EM wave frequency

In summary, photons composing blue light have a higher frequency, momentum, and energy compared to those composing red light. The differentiation of 1,000 photons with energy E and 2,000 photons with energy E/2 can be detected through multi-photon absorption or the photo-electric effect, which relies solely on the frequency of the photons and not their amplitude or wavelength. This may seem counterintuitive, but it is a fundamental principle in understanding the behavior of photons.
  • #1
humbleteleskop
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Do individual photons have some attributes which relate to EM wave frequency? In other words, is there any difference in photons composing a red and blue beam of light?
 
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  • #2
Certainly, photons composing blue light have a higher frequency which means they have a higher momentum, and a higher energy.
 
  • #3
Matterwave said:
Certainly, photons composing blue light have a higher frequency which means they have a higher momentum, and a higher energy.

I didn't think frequency could be attributed to individual photons.

How do we differentiate 1,000 photons each having energy E, from 2,000 photons having energy E/2? What would be the instrument or type of sensor that could tell that difference?
 
  • #4
humbleteleskop said:
I didn't think frequency could be attributed to individual photons.

How do we differentiate 1,000 photons each having energy E, from 2,000 photons having energy E/2? What would be the instrument or type of sensor that could tell that difference?


If all of the photons hit at the same time, and in the same small area, you could get multi-photon absorption - 1,2,3, or more photons absorbed by each process. But the statistics will not be uniform, so you can tell; but this requires the conditions when non-linear optics is required.

The photo-electric effect (see Einstein, 1905: http://en.wikipedia.org/wiki/Photoelectric_effect) applies in most ordinary circumstances - and then the metal plate has no trouble telling the difference between photons with energy higher than the work function barrier, and those below.
 
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  • #5
Interesting. Especially the part how neither amplitude nor wavelength are responsible for the effect, but frequency alone. Which doesn't really make sense to me as I understand all three are proportionally correlated, so I don't see how frequency can be independent of the other two in such way.
 
  • #6
humbleteleskop said:
Interesting. Especially the part how neither amplitude nor wavelength are responsible for the effect, but frequency alone. Which doesn't really make sense to me as I understand all three are proportionally correlated, so I don't see how frequency can be independent of the other two in such way.

Wavelength and frequency are (of course) correlated, but amplitude can be varied independently. The surprising and counterintuitive thing about the the photoelectric effect is that it doesn't matter how much you dial up the amplitude and therefore how much energy is transferred to the target - you won't get any electron emission if the frequency is too low (equivalently, if the wavelength is too great).
 
  • #7
Yes, I always thought that the wavelength was c/f. I don't think a single photon had an amplitude though.
 
  • #8
Jilang said:
Yes, I always thought that the wavelength was c/f. I don't think a single photon had an amplitude though.

It doesn't. Electromagnetic radiation has an amplitude, and that determines (sort of) the number of photons.
 

1. What is the relationship between photons and electromagnetic (EM) wave frequency?

Photons are the fundamental particles that make up electromagnetic waves. The energy of a photon is directly proportional to the frequency of the EM wave. This means that as the frequency of an EM wave increases, so does the energy of the photons making up the wave.

2. How does the frequency of an EM wave affect its properties?

The frequency of an EM wave determines its properties, such as wavelength, energy, and polarization. Higher frequency waves have shorter wavelengths, higher energy, and are more likely to be polarized. Lower frequency waves have longer wavelengths, lower energy, and are less likely to be polarized.

3. Can photons exist without an EM wave?

No, photons cannot exist without an EM wave. They are the carriers of electromagnetic energy and are always associated with an EM wave. Without an EM wave, there would be no photons.

4. How are photons and EM waves related to the electromagnetic spectrum?

The electromagnetic spectrum is a range of all possible frequencies of EM waves, including radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. Each of these types of waves consists of photons with different frequencies, energies, and properties. The electromagnetic spectrum shows the relationship between photons and EM wave frequency.

5. How does the relationship between photons and EM wave frequency impact technology?

The relationship between photons and EM wave frequency has a significant impact on technology. Different frequencies of EM waves allow us to use different technologies, such as radio communication, X-ray imaging, and infrared cameras. The ability to manipulate and harness the frequency of EM waves has led to advancements in various fields, including telecommunications, medicine, and astronomy.

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