A Welch model 2639 'Electron Diffraction tube' is used in an experiment in the second year lab. The tube has graphite and aluminum foils mounted on a grid between the electron gun and the screen of ...

To separate white light into these colors, the light needs to pass through a material that “bends” it ... Take one of the 4″ × 4″ pieces of foil and tear or cut a small hole in the center of it — a ...