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What frequency means for a single photon?

elias2010
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    It is the rate at which the electrical (or magnetic) vector changes direction. Or it is a measure of the energy. What do you think the answer should be? – Floris Jan 09 '15 at 23:52
  • The vector don't change a single photon has one peak that is a half-period (T) T=1/frequency – elias2010 Jan 10 '15 at 21:21

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Frequency is inversely proportional to the wavelength of the photon and so in another way of indicating the energy of the photon. Remember that for a given wavelength/frequency, your photon will have a specific energy given by $$E = \text{a constant} \times \text{frequency} = \frac{\text{a constant}}{\text{wavelength}}$$ All these values measure the same thing.

HDE 226868
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Cauchy Kun
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It is the very well-known, which is also determines the Planck constant too:

$$f=\frac{E}{h}$$

Here $h$ is the Planck-constant, around $6.6*10^{-34} \frac{J}{s}$.

If you have mass, you can convert this to energy by the well known $E=mc^2$ formula.

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    No ,you cannot do that with $E=mc^2$ ,rather you should use $E=pc$.a photon cannot have mass. – Paul Jan 10 '15 at 04:12
  • Why photon has to not have mass instead of a relativistic formula to be wrong? – elias2010 Jan 10 '15 at 16:49
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    You can use $E=mc^2$ for a photon, since according to Einstein mass and energy are equivalent. The rest mass is zero, though. – kotozna Feb 22 '15 at 16:37
  • Indeed, the relativistic form is $E^2 = (mc^2)^2 + (pc)^2$, and since rest mass is zero, it simplifies to $E = pc$. – Fax Jan 10 '21 at 17:08