BLACKBODY RADIATIONPresented by Group 6:
Neal Boseman, Vessen Hopkins, and Sarah Moorman
Topics of Discussion: What is Blackbody Radiation?
History of Blackbody Radiation
How has this discovery impacted Modern Physics?
Applications of Blackbody Radiation
Gustav Kirchhoff
German physicist 3/12/1824 –
10/17/1887 Contributed in the
Areas of:- Electrical
Circuits- Spectroscopy- Blackbody
RadiationImage Credit: Hulton Archive/Getty Images
Spectroscopy
Spectroscopy - is the scientific study of an object based on the dispersion of said object’s light into its component colors.
Kirchhoff’s Laws
1. Hot, dense object will produce a Continuous Spectrum.
- This is what Kirchhoff termed a Blackbody.
2. Hot, low density object will produce an Emission Line Spectrum.
3. A cool, low density gas in front of a continuous light source will produce an Absorption Line Spectrum.
Blackbody
Theorized in 1859 by Gustav Kirchhoff.
An ideal physical body.
Absorbs 100% of all incident radiation and reflects or transmits none.
Emits 100% radiation. Image Credit: NASA
Blackbody Radiation A Blackbody in thermal equilibrium emits
EM radiation termed Blackbody Radiation. Universal Property: Independent of
material used. Led to relation between radiation
intensity (I), temperature (T), and wavelength ( λ ).
Blackbody Curves Helped prove thermal radiation was also
EM radiation. Many physicist attempted to characterize
shape of Blackbody curve…
Blackbody Radiation
Image credit: http://hyperphysics.phy-astr.gsu.edu
Attempts to Find Best Fit Formula
Wien’s Displacement Law: Relation between peak wavelength
and temperature. Stefan-Boltzmann Law:
Relation between temperatureand the power per unit area.
Rayleigh-Jeans Formula: Relation between radiation
intensity, temperature, andwavelength. Ultraviolet Catastrophe!
Raleigh-Jeans Law
Image credit: http://hyperphysics.phy-astr.gsu.edu
Failures to Model Blackbody Curves
Rayleigh-Jeans Formula Rayleigh-Jeans model failed to comply with
experimental data at high frequencies
Wien’s Radiation Law Wien's model failed to comply with
experimental data at low frequencies.
Max Planck (Apr. 1858 to Oct.
1947) Approach to Blackbody
Radiation Problem Planck’s Radiation Law
Mathematical Trick h = Planck’s Constant Discrete Values of
Energy: E = nhf
Image credit: Hulton Archive/Getty Images
How Did Blackbody Radiation Impact Modern Physics?
Led to established relationships between light intensity, wavelength, and temperature:
Wien’s Displacement Law Stefan-Boltzmann Law Rayleigh-Jeans FormulaUV Catastrophe
Planck’s Radiation Law Discrete Values Led to Best Fit for
Experimental Data – Planck’s Mathematical Guess
Thus We Have Quantization of Energy: E = nhf
Implications for What’s Occurring at Atomic Level.
Birth of Quantum Mechanics!
Applications of Blackbody Radiation
Gave people the ability to calculate temperatures of distance cosmic bodies
Inspired new devices such as thermal vision and new types of thermometers
Acknowledgements/References
Thornton, Stephen T., and Andrew F. Rex. "The Experimental Basis of Quantum Physics."Modern Physics for Scientists and Engineers. 4th ed. Boston, MA: Cengage Learning, 2013. N. pag. Print.
Kirchhoff, G. (1860). "Ueber das Verhältniss zwischen dem Emissionsvermögen und dem Absorptionsvermögen der Körper für Wärme and Licht". Annalen der Physik und Chemie 109 (2): 275–301.Bibcode:1860AnP...185..275K. doi:10.1002/andp.18601850205. Translated by Guthrie, F. as Kirchhoff, G. (1860). "On the relation between the radiating and absorbing powers of different bodies for light and heat". Philosophical Magazine. Series 4 20: 1–21.
Planck, Max (1901). "On the Law of Distribution of Energy in the Normal Spectrum".Annalen der Physik 4: 553. Bibcode:1901AnP...309..553P.doi:10.1002/andp.19013090310.
Fowler, Michael. "Planck’s Route to the Black Body Radiation Formula and Quantization." Lecture. 25 July 2008. Web. 1 Dec. 2013.
Q & A