Blackbody radiation theory explains why our |
sun glows white, your stove top element glows
red and your dog, hopefully, glows not at all.
What is Blackbody Radiation? Everytime you enjoy sunlight, or turn on a light bulb you are experiencing the benefits of blackbody radiation.
Radiation, or more precisely, electromagnetic radiation, is generated by the oscillation of electric charge.
The radiation which comes from the sun, a light bulb or any heated object is a direct result of the vibration of electrons and other charged particles from which the material is composed. In hotter objects the particles vibrate more, and therefore emit more blackbody radiation.
The phenomena is the same whether the radiation is coming from our sun, your stove or your dog. Warm bodies give off radiation, warmer bodies not only give off more radiation but higher frequencies of radiation. That is why our sun glows white, your stove top element glows red and your dog, hopefully doesn't glow at all, but simply feels warm to the touch.
Blackbody Radiation vs Temperature The anyalysis of how and why blackbody radiation varies with the internal temperature of the radiating material is a key piece in the quantum mechanics
puzzle which lead to the acceptance of Shrodinger's equation as the defining equation of motion within our submicroscopic world.
The two curves on the right illustrate the classical and the quantum predictions of how blackbody radiation will vary with frequency at a given temperature.
Both models predict that at higher temperatures more radiative energy is released, however only the quantum model is well behaved at higher frequencies, predicting that the radiation level will peak at a specific frequency and then decline to zero, rather than 'blow up' as the classical model does for indefinitely increasing frequencies.
Equipartiion of EnergyBoth models make use of a principle called 'the Equipartion of Energy.' That is, they assume that the available heat energy in the the system will, on average, be divided equally among all the available modes of vibration within the system.
By identifying and counting the available oscillation modes and their frequencies, we can predict the amount of radiative energy which will be emitted at each frequency.