PLANET EARTH

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# PLANET EARTH - PowerPoint PPT Presentation

PLANET EARTH. LIGHT. 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. Source. Observations - visible

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### PLANETEARTH

LIGHT

Lab Experiments
• Distance Behavior - I = A/r2 +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 = I0• e-•d
Source
• Observations - visible
• for Hydrogen
• 1/ = R(1/22 - 1/n2) , R = 1.097 •107 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.
Bohr Model
• Quantized energy levels exist in all atoms.
• For Hydrogen the energy of each level is
• En = 13.6/n2
• 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.
• Is this consistent with the “observations” on the previous slide.
Bohr & Empirical
• E2-n = 13.6 (1/22-1/n2) Bohr theory
• hc/  = E2-n energy emitted as a photon
• Then 1/  = 13.6/hc (1/22-1/n2)
• Does 13.6/hc = R ?
Constants
• R = 1.095x107 m-1
• h = 6.626x10-34 joule-sec
• 1 ev = 1.6x10-19 joules
• c = 3x108 m/sec