Why do soap bubbles have rainbow colors?
Show answer & explanation
Answer: Thin film interference patterns
Thin film interference patterns ✓ — Correct! Thin film interference! Bubble wall has two surfaces (front and back). Light reflects from both—waves recombine. Film thickness (wavelength-scale) determines which colors constructively interfere (brighten) vs destructively interfere (cancel). Thickness varies across bubble—different areas show different colors. As bubble thins, colors shift (thicker=red, thinner=blue/violet). Just before popping, bubble appears black (too thin for visible light interference). Oil slicks show same phenomenon!
Water refracts like prism — Wrong. Water can refract, but bubble colors are interference pattern from light waves reflecting off front/back surfaces, not dispersion.
Light bounces multiple times — Wrong. Multiple reflections occur, but colors arise from interference—waves from front and back surfaces combining constructively or destructively.