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For hot bodies we generally draw graph between intensity and wavelength similar to one in picture.

  1. My question is this graph really continous?
  2. If it is continuous, does it not mean there are infinte wavelengths between any two given wavelengths and we have a photon corresponding to each one of them, thus infinite photons, which would amount to infinite energy
  3. if it is not really continuous then, how do we know which wavelength photon are being released and which wavelength photons are missing?

https://i.stack.imgur.com/53KJv.jpg , I am sorry i did not know how to insert pic properly

Michael Seifert
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bdogwjumiz
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  • TLDR: The graph is a limit. A hot object will emit a finite number of photons in a finite span of time. If you collect those photons, and sort them into a finite number of energy "bins," you can make a histogram. As the number of bins, and the number of photons collected increase without bound, the shape of the histogram will approach the shape of the graph. – Solomon Slow Dec 14 '23 at 18:44
  • Also, the frequency of each photon detected within a certain amount of time will necessarily have some broadening due to energy/time uncertainty. Thus the resolution of any frequency measurement is fundamentally limited by the measurement duration. – Gilbert Dec 14 '23 at 19:51

1 Answers1

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A true blackbody spectrum is continuous. There is some probability that you could detect a photon with any frequency. The continuous Planck curve is a predicted distribution of the probability of photon frequencies. If you have a very large number of photons then their frequency distribution should match that predicted.

Obviously, in any finite experiment, you will detect a finite number of photons and those photons will have particular frequencies (within the accuracy with which you can measure them). So in that sense, any real experiment will have some discretisation.

ProfRob
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