Step 1: Soap film structure: A soap film, like a bubble, is a thin water layer between soap molecules. Its thickness is similar to visible light wavelengths.
Step 2: Light interaction: When white light hits the film, some reflects off the top, and some enters and reflects off the bottom.
Step 3: Interference principle: The two reflected light waves take slightly different paths. They recombine and interfere. Constructive interference brightens certain colors, while destructive interference cancels them. Non-uniform film thickness creates varied colors.
Step 4: Additional concepts: - Diffraction: Wave bending around an obstacle. - Scattering: Light redirection by particles (e.g., blue sky). - Dispersion: White light splitting into colors via a prism due to different refractive indices.