Black body radiation

10,939 views 10 slides Feb 19, 2012
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DISUSUN OLEH BLACK BODY RADIATION Rahmawati Th. Diamanti Ivone Pudihang Recky Lasut Aulinda Tambuwun Deyvita Montolalu

What is a Black Body ? A black body is an ideal body which allows the whole of the incident radiation to pass into itself ( without reflecting the energy ) and absorbs within itself this whole incident radiation (without passing on the energy).

Black body radiation curves showing peak wavelengths at various temperatures The graph shows:  As the temperature increases, the peak wavelength emitted by the black body decreases. As temperature increases, the total energy emitted increases, because the total area under the curve increases. 

BLACK BODY RADIATION LAW The Rayleigh-Jeans Law. It agrees with experimental measurements for long wavelengths. It predicts an energy output that diverges towards infinity as wavelengths grow smaller. The failure has become known as the ultraviolet catastrophe

Planck's law of blackbody radiation where I ( ν , T ) is the  energy  per unit  time  (or the  power ) radiated per unit area of emitting surface in the  normal  direction per unit  solid angle  per unit  frequency  by a black body at temperature T ; h  is the  Planck constant ; c  is the  speed of light  in a vacuum; k  is the  Boltzmann constant ; ν  is the  frequency  of the electromagnetic radiation; and T  is the  temperature  of the body in  kelvins .

Wien's displacement law Wien's displacement law  shows how the spectrum of black body radiation at any temperature is related to the spectrum at any other temperature. If we know the shape of the spectrum at one temperature, we can calculate the shape at any other temperature. A consequence of Wien's displacement law is that the wavelength at which the intensity of the radiation produced by a black body is at a maximum,  λ max , it is a function only of the temperature

Stefan-Boltzmann Law The   Stefan–Boltzmann law  states that the power emitted per unit area of the surface of a black body is directly proportional to the fourth power of its absolute temperature: where   j *is the total power radiated per unit area,  T  is the  absolute temperature  and  σ  = 5.67×10−8  W m −2  K −4  is the  Stefan–Boltzmann constant .

BENCANA ULTRAVIOLET when the actual radiation emitted from a black-body was measured, it was seen not to shoot toward in infinite at the ultraviolet region of the electromagnetic scale (as the theories suggested), but rather to be highest toward the middle of the visible range of the spectrum, which seemed entirely counter-intuitive. It is for this reason that the discrepancy became known as  The Ultraviolet Catastrophe .

CONCLUSION Blackbody radiation does not depend on the type of object emitting it. Entire spectrum of blackbody radiation depends on only one parameter, the temperature, T

T H N K Y O U A
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