1. Radiation Curves

2. Continuous Radiation How bright is the continuous spectrum at different colors? How does a perfect light source emit its light? 400nm 500nm 600nm 700nm

3. Early Experiments Darken inside with carbon black Measure radiation that emerges from hole Blackbody Radiation

4. Vis IR UV

5. Changes with Temperature * Visible 5000 K 6000 K 7000 K * *

6. Wien’s Displacement Law The wavelength of the peak of the blackbody curve is inversely proportional to the temperature. Cool stars are red - hot stars are blue Wilhelm Wien

7. Total Energy

8. Stefan-Boltzmann Law Area under the blackbody curve measures the total energy output of the source and is proportional to T 4. Josef Stefan Ludwig Boltzmann

9. 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

10. ORION

11. Some Real Stars Rigel 11500 K Sirius A 10000 K The Sun 5800 K

12. More Real Stars The Sun 5800 K Capell a 5200 K Betelgeuse 3600 K

13. Review Animation

14. Two-Dimensional Spectra Continuous Emission Absorption

15. Visible Light Infrared Light The Orion Nebula