A beam of white light refracts through a glass prism, splitting into a spectrum of colors - the same effect Isaac Newton first demonstrated in 1666 to prove that ordinary "white" light is actually a mixture of colors, not a pure substance. Dispersion happens because glass bends each wavelength by a slightly different amount (Snell's law: n1 sin theta1 = n2 sin theta2), and glass's refractive index is higher for short wavelengths than long ones - so violet light (around 400nm) bends more than red light (around 700nm), fanning white light into the visible spectrum of roughly 380-700 nanometers. This "normal dispersion" is the same physics behind natural rainbows, where sunlight refracts and reflects inside raindrops. Drag to orbit, scroll to zoom.