Ultraviolet Catastrophe

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David Tellez Lec 3
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Ultraviolet Catastrophe

Postby David Tellez Lec 3 » Sun Oct 19, 2014 11:15 pm

Why does the concept of ultraviolet catastrophe, in classical physics, predict that any hot body should emit ultraviolet radiation?

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Re: Ultraviolet Catastrophe

Postby Chem_Mod » Tue Oct 21, 2014 10:32 am

It is called the ultraviolet catastrophe because classical physics predicted (using Rayleigh–Jeans equation) that a hot body would emit energy at all wavelengths including short wavelengths. Experiments showed that very short wavelengths (high energy) were not emitted.

If you are asking why the classical theory (Rayleigh–Jeans equation) predicted that short wavelengths should be emitted. The answer is it assumed equipartition of energy which implies all wavelengths would be equally emitted.

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Re: Ultraviolet Catastrophe

Postby YashDeshmukh1D » Wed Oct 11, 2017 10:21 am

How exactly does Planck's hypothesis solve the ultraviolet catastrophe? Even if bodies require a minimum threshold of energy to emit certain frequencies (quantum theory), why would that imply a maximum limit that stops bodies from emitting high energy radiation that "lays waste to the countryside?"

Andrea ORiordan 1L
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Re: Ultraviolet Catastrophe

Postby Andrea ORiordan 1L » Thu Oct 12, 2017 4:12 pm

Classical physics assumes than an oscillator (i.e. a charged particle) could oscillate at any energy, and therefore emit electromagnetic radiation at very high frequencies. Planck's hypothesis says that radiation of higher frequencies can only be generated when an oscillator of that higher frequency has enough energy to start oscillating in the first place. At lower temperatures (i.e. body temperature), there is simply not enough energy to stimulate oscillations at higher frequencies.

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