Black Body Radiation: Classical Mechanics Can't Explain It

In summary, according to the discussion thread, classical mechanics cannot explain black body radiation because it does not account for the discreteness of energy values of harmonic oscillators. This is in contrast to experimental data which shows a decrease in energy as the wavelength approaches zero. The constant of Planck was created to address this discrepancy.
  • #1
ohhhnooo
10
0
why can't classcial mechanic explain black body radiation?
 
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  • #3
ohhhnooo said:
why can't classcial mechanic explain black body radiation?

Because if you calculate the number of possible configurations as a function of the emitted wavelength and the temperature (the socalled Rayleigh-Jeans spectral distribution) you can use this quantity to calculate the emitted energy by integrating over the wavelengths. Now, (and here is the problem) if you calculate this energy and you insert very low values for lambda (ie if the wavelength evolves toward 0) you will get an infinetely large energy-value. This is NOT in correspondence with experimental data, because if lambda goes to ZERO, this energy should LOWER instead of rising. The solution was that the involved harmonic oscillators had to have discrete energy values in stead of any finite arbitrary value (as in classical physics).

regards
marlon

ps : this is how the constant of Planck was born
 

What is black body radiation?

Black body radiation is the electromagnetic radiation emitted from a perfect black body, which is an idealized object that absorbs all radiation that falls on it. It is a fundamental concept in physics and plays a crucial role in understanding the behavior of matter at high temperatures.

Why can't classical mechanics explain black body radiation?

Classical mechanics, which is based on Newton's laws of motion, fails to accurately predict the behavior of matter at high temperatures. This is because classical mechanics does not take into account the wave-like nature of electromagnetic radiation, which is necessary to explain black body radiation. This led to the development of quantum mechanics, which successfully explains black body radiation.

How is black body radiation related to temperature?

According to the Planck's law, the intensity of black body radiation is directly proportional to the fourth power of temperature. This means that as the temperature of a black body increases, the amount of radiation it emits also increases significantly.

What is the significance of the Stefan-Boltzmann law in black body radiation?

The Stefan-Boltzmann law states that the total energy emitted per unit area by a black body is proportional to the fourth power of its absolute temperature. This law is important in understanding the amount of energy radiated from a black body and has practical applications in fields such as astrophysics and thermodynamics.

Can black body radiation be observed in real-life?

Yes, black body radiation can be observed in various natural phenomena, such as the thermal radiation from the sun and stars, the glowing of hot objects like lava or fire, and the heat emitted from our bodies. It is also utilized in many modern technologies, such as infrared cameras and thermal imaging devices.

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