The discussion focuses on the wave model of light, specifically its ability to explain interference patterns that the particle model cannot. The key behavior in question is the interference of light waves, which occurs when light passes through a diffraction grating. This setup allows for the observation of light and dark bands, indicative of constructive and destructive interference. The classic Young's experiment demonstrates this phenomenon, where monochromatic light is directed through a single slit and then through a double slit, resulting in an interference pattern that reveals the wavelength of the light. The wave model effectively accounts for these patterns, highlighting the significance of wave behavior in understanding light's properties.