How Einstein used the photoelectric effect to promote his theory of light being made of particles. Discuss the term photosensitive, and explain why electrons in distant atomic orbits are not held as tightly to the nucleus, and if supplied with sufficient energy, will escape the nuclear attraction. Show that only high frequencies of light will demonstrate the effect, and that low frequencies (red and orange) regardless of the intensity, will not cause electrons to leave the metal. Show an image of Young's double slit experiment and then an image of the same diffraction pattern when a beam of electrons is used in place of a beam of light.