The formation of bright colors in the thin lather of soap is the result of multiple reflection and interference (A). When light strikes the soap film, some of it is reflected off the outer surface, while the rest penetrates the film and is reflected off the inner surface. The reflected light waves from these two surfaces can interfere with each other constructively or destructively, depending on the thickness of the film and the wavelength of the light. Constructive interference enhances certain wavelengths, making specific colors appear more vivid, while destructive interference cancels out other wavelengths. This phenomenon creates the shifting patterns of vibrant colors observed in soap bubbles and thin soap films. The colors vary with the film’s thickness and the angle of observation, demonstrating the interplay of light wave interference in thin films.