Kasha's rule

Kasha's rule is when something absorbs light, it gets excited and starts to wobble like a jiggling jellybean. When this happens, it can give off light too, but the color of the light depends on how much wobbling happens. So if something absorbs blue light, it wobbles a lot and gives off red light. But if it absorbs red light, it wobbles just a little and gives off blue light. This rule helps scientists study things like molecules and atoms by looking at what kind of light they give off when they get excited.