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