1. Why Light, why now?

2. Its all about the electrons. . .

3. When hydrogen gas is heated, or a current passes through it, light is given off.
Only certain wavelengths of light are given off.

4. Where does the light come from?
Atomic Emission Spectrum

5. It depends on the electrons

6. What causes the spectra?

7. Hydrogen
Helium
Carbon

8. Atomic Spectra

9. Light Energy Energy travels as waves.
at a constant speed (3 x 108 m/s).
E = hf = hc/l
h = Planck’s constant = x J•s
f = frequency
c = speed of light = 3.00 x 108m/s
l = wavelength 

10. The Electromagnetic Spectrum
E = hf

11. In Summary
E = hf