Blackbody Radiation quantum mechanics.pptx

Blackbody Radiation quantum mechanics.pptx

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  Blackbody radiation Supervisor Dr Hsu MyatAung,Lecturer Department of Physics East Yangon University Present by Group I 4th year physics 30.1.2024 1
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  ABSTRACT • Blackbody radiationis a cornerstone in the study of quantum mechanics. • This experiment is what led to the discovery of a field that would revolutionize physics and chemistry. • Quantum mechanics gives a more complete understanding of the fundamental mechanisms at the sub-atomic level. 2
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  INTRODUCTION • In thelate 19th century, scientists thought the laws of physics could explain everything in nature. • They believed nature consisted of particles following Newton’s laws and radiation following Maxwell’s equations—now called classical physics laws. • However, experiments, including those on blackbody radiation, challenged these classical laws, paving the way for the modern concept of physics. 3
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  FIGURE:A BLACKBODY REPRESENTEDBY A SMALL HOLE IN THE WALL OF A CAVITY • A blackbody is a perfect radiator of light that absorbs and emits all radiations incident on it. • Its light output depends on its temperature. The sun and stars emit radiation like a blackbody A blackbody is physically realized by a cavity radiator with a small hole in the wall as shown in Figure. BLACKBODY RADIATION 4
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  BLACKBODY RADIATION’S LAWS •In blackbody radiation, there are essential laws that explain its basic features, and these laws are at the core of quantum theory. 1.Planck's Law 2.Wien's Law or Wien's Displacement Law 3.Stefan-Boltzmann’s Law 5
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  1. PLANCK'S LAW •Planck's law gives the amount of radiation emitted per unit solid angle in terms of wavelength or frequency (λ) and equilibrium temperature (T). Where, B = Spectral radiance λ = Wavelength of radiation T = Absolute temperature c = Speed of light h = Planck's constant 6
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  2.WIEN'S LAW ORWIEN'S DISPLACEMENT LAW • Wien's law states that the wavelength at which a blackbody emits radiation with maximum intensity is inversely proportional to the absolute temperature. • (λmax = b/T) Where, λmax = (peak wavelength) b = Wien's constant T = absolute temperature 7
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  3.STEFAN-BOLTZMANN'S LAW • Stefan-Boltzmann'slaw states that the total radiant power emitted by a surface across all wavelengths is proportional to the fourth power of its absolute temperature. • Therefore, the total energy radiated by a blackbody depends on its temperature. Where, P = Radiant power A = Surface area T= Absolute temperature σ =Stefan-Boltzmann Constant 8
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  BLACKBODY RADIATION GRAPH •Stars, our celestial examples of blackbodies, reveal their temperature through radiation curves. • The hottest stars emit ultraviolet radiation at surface temperatures of K. • Cooler stars, like our Sun at 6,000 K, shine in the visible spectrum. • Even cooler stars emit infrared radiation. • Humans, being cold objects, also emit infrared radiation. Special telescopes help us see the invisible ultraviolet and infrared rays emitted by these stellar bodies. 9
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  CONCLUSION • Blackbody radiationis a fundamental concept in physics that describes the behavior of electromagnetic radiation in different systems. • Blackbody radiation has numerous applications and is a crucial concept in the history of physics, with a significant impact on the development of quantum mechanics. 10
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  REFERENCES • Grade-10 PhysicsTextbook Website References ● https://en.m.wikipedia.org/wiki/Black-body_radiation ● https://www.facebook.com/basiclevelofphysics.blp?mib extid=ZbWKwL ● https://www.sciencefacts.net/plancks-law.html 11
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