Photon Kinetic Energy: Wavelength & Frequency

In summary, the energy of a photon is determined by its frequency, which is related to its wavelength and Planck's constant. The proper relativistic equation for photons is E^2 = p^2c^2 + m^2 c^4. For ordinary particles, the equation E = \sqrt{p^2c^2 + m^2 c^4} can be used, but for photons, the equation is E = pc. According to de Broglie, p = h \nu. The equations E=1/2mv^2 and E=mc^2 cannot be applied to photons."
  • #1
nuby
336
0
How is a photon's energy determine in relation to it's wavelength and frequency?
For example, 20hz vs. 400ghz electromagnetic waves.
 
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  • #2
nuby said:
How is a photon's energy determine in relation to it's wavelength and frequency?
For example, 20hz vs. 400ghz electromagnetic waves.
The energy of a photon, E (which can be considered as all kinetic energy since the proper energy = E0 = 0 and E = K + E0 = K), is related to the photon's frequency, f, by E = hf where h = Planck's constant = 6.626068 × 10-34m2kg/s.

Pete
 
  • #3
can E=1/2mv^2 be applied to photons ever?
or E=mc^2
 
  • #4
The proper relativistic equation is
:[tex]E^2 = p^2c^2 + m^2 c^4[/tex], which works just fine for photons when [tex]m = 0[/tex].

For ordinary particles, one can Taylor expand [tex]E = \sqrt{p^2c^2 + m^2 c^4}[/tex] to get a non-relativistic equation most people use... but for photons, you can't do this, and [tex]E = pc[/tex] simply.

According to de Broglie, [tex]p = h \nu[/tex], of course.
 
  • #5
nuby said:
can E=1/2mv^2 be applied to photons ever?
or E=mc^2
No.

Pete
 

1. What is photon kinetic energy?

Photon kinetic energy refers to the energy that a photon possesses due to its motion. It is a type of electromagnetic energy and is directly related to a photon's wavelength and frequency.

2. How are wavelength and frequency related to photon kinetic energy?

Wavelength and frequency are inversely proportional to photon kinetic energy. This means that as the wavelength increases, the frequency decreases and vice versa. This relationship is described by the equation E = hν, where E represents photon kinetic energy, h is Planck's constant, and ν is frequency.

3. Can photon kinetic energy be measured?

Yes, photon kinetic energy can be measured using various scientific instruments such as spectrometers. These instruments can measure the wavelength and frequency of photons and calculate their kinetic energy using the equation mentioned above.

4. How is photon kinetic energy important in the field of physics?

Photon kinetic energy is crucial in understanding various phenomena in the field of physics, such as the photoelectric effect and the emission of light from atoms. It also plays a significant role in technologies that utilize light, such as lasers and solar panels.

5. Is there a limit to the amount of photon kinetic energy?

No, there is no limit to the amount of photon kinetic energy. As the frequency of a photon increases, its energy also increases. This means that there is no upper limit to the energy that a photon can possess, although it becomes increasingly difficult to produce and detect photons with very high energies.

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