2. PLANET EARTH LIGHT

3. Lab Experiments Distance Behavior - I = A/r 2 +B Definition of color - The ratio of two colors at the same distance. Color and Temperature - objects get more “blue” with increasing temperature. Attenuation I = I 0 e -d

4. Source Observations - visible –for Hydrogen –1/ = R(1/2 2 - 1/n 2 ), R = 1.097 10 -7 m -1 –n = 3 red light = 6562 10 -10 –n = 4 blue light = 4861 10 -10 –This is an empirical formula! –Each atom has a unique spectrum! –Formulas like this, give the colors of light that come out of atoms.

5. Bohr Model Quantized energy levels exist in all atoms. For Hydrogen the energy of each level is –E n = 13.6/n 2 Transitions between levels either absorb or release energy. Energy is released in the form of light packets or photons each of energy: –E = h  c/ = h  f Einstein postulates this for PE effect –the energy available is the difference between the two levels involved in the transition. This is consistent with the “observations” on the previous slide.