What is an example of interference?

Example of Interference: Thin Film Interference

Thin film interference is a phenomenon that occurs when light waves reflected by the upper and lower boundaries of a thin film interfere with one another, either enhancing or reducing the light's intensity. This type of interference is responsible for the colorful patterns seen in soap bubbles, oil slicks on water, and thin layers of oxide on metals.

When light encounters a thin film, part of the light is reflected off the top surface of the film, and part enters the film, reflecting off the bottom surface before emerging back into the air. The two reflected light waves can interfere constructively or destructively depending on the thickness of the film, the wavelength of the light, and the angle of incidence.

Constructive interference occurs when the path difference between the two waves is an integer multiple of the wavelength, leading to a brightening of the light. Destructive interference happens when the path difference is a half-integer multiple of the wavelength, causing the light to diminish or cancel out.

The variation in film thickness and the angle of light incidence result in different colors being observed due to the wavelength-dependent nature of interference. This phenomenon is not only beautiful but also has practical applications in optical coatings, anti-reflective coatings, and enhancing the efficiency of solar cells.