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Radiation Curves. 400nm 500nm 600nm 700nm. Continuous Radiation. How bright is the continuous spectrum at different colors? How does a perfect light source emit its light?. Early Experiments. Blackbody Radiation. Darken inside with carbon black.
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400nm 500nm 600nm 700nm Continuous Radiation • How bright is the continuous spectrum at different colors? • How does a perfect light source emit its light?
Early Experiments Blackbody Radiation Darken inside with carbon black Measure radiation that emerges from hole
Blackbody Radiation Vis UV IR
Changes with Temperature Visible * 7000 K * 6000 K * 5000 K
Wien’s Displacement Law • The wavelength of the peak of the blackbody curve is inversely proportional to the temperature. Wilhelm Wien Cool stars are red - hot stars are blue
Stefan-Boltzmann Law • Area under the blackbody curve measures the total energy output of the source and is proportional to T4. Ludwig Boltzmann Josef Stefan
Blackbody Radiation • Everything in nature emits light • The type of light emitted depends on the temperature of the source • The walls of this room • IR • Stars • Visible and UV • The Corona of the Sun (2,000,000 K) • X-rays
Some Real Stars Rigel 11500 K Sirius A 10000 K The Sun 5800 K
More Real Stars The Sun 5800 K Capella 5200 K Betelgeuse 3600 K
Review • Animation
Continuous Emission Absorption Two-Dimensional Spectra
The Orion Nebula Visible Light Infrared Light