Spectral Line Experiment
Complete before lecture starts at 2:05!

Get a diffraction grating
    ...a series of mini-prisms acting as one big prism

Look at a bright light to find the rainbow off to the side.

Look at Hydrogen & Helium gas discharge tubes
    ...see their characteristic spectral emission lines?

Franhofer's invention
    - diffraction grating discoveryof absorption lines

As you exit, be sure to hand in your grating