Interference in a Soap Film
Purpose
Students observe thin film interference as colored bands form in a soap film and evolve over time. The projected image shows how constructive and destructive interference between reflections from the front and back surfaces produce wavelength-dependent patterns that shift as the film thins under gravity.
Figure 1:
Magnified projection of soap film interference patterns showing characteristic colored bands resulting from constructive and destructive interference between reflections from the front and back surfaces of the thin film.
Figure 2:
Complete optical arrangement showing fiber optic illumination, collimating lens system, and soap film box positioned to project interference patterns onto a screen via reflection.
Figure 3:
Side view demonstrating the optical rail configuration with adjustable components for aligning the illumination, soap film ring, and projection lens to achieve proper focus and image magnification.
Demo Apparatus
- 1