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As classical physics predicted the black body spectrum should be a rational graph where the radiation reaches up unlimited high with the increase of frequency. However, it doesn't meet the experimental result where the black body spectrum dip down in the UV spectrum and didn't go up based on the classical theory. Then Quantum theory has been discovered to answer this inconsistent.

So, my question is how quantum theory explained the dip down at the UV portion that happened in the black body spectrum and also afterward why would the radiation meet the peak and went down with the increase of wavelength.

Qmechanic
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TEH CHUN SHEN Moe
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It is directly related to temperature. The spectrum you are looking at is related more to our sun and similar temperatures. Cooler temperatures have peaks at the longer wavelengths and hotter temps have peaks in the ultra violet or even shorter wavelength. enter image description here As for why there is a peak, think of it this way. Photons carry the energy away. The higher frequencies (shorter wavelengths) carry more energy away and cool the body faster. The lower frequencies (longer wavelengths) carry less energy away. Photons are emitted at all frequencies up to a limit proportional to temperature. Somewhere in the middle there’s a peak range of frequencies. The peak is not an average it’s the most common frequency. For example the frequencies we call visible light are the most common frequencies emitted by our sun. And millions of years of evolution have evolved our eyes to see those frequencies.

Bill Alsept
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    Instead of this, I would like to know why the curve goes down tremendously at the left-hand side? Also, are there all goes to zero or it's just approaching to zero? – TEH CHUN SHEN Moe Sep 19 '21 at 08:39
  • Look at this link, it is the same for the classical expectation too http://hyperphysics.phy-astr.gsu.edu/hbase/mod6.html – anna v Sep 19 '21 at 09:03