A thin layer of gasoline floating on water appears brightly colored in sunlight. From where do the colors come?

1 ... the interference of light waves reflected from the opposite surfaces of the gasoline film

2. the interference of the various wavelengths of sunlight reflected at the air‑gasoline boundary

3. the interference of light waves of similar frequencies created by the dispersion of the sunlight by the gasoline film

4. the interference of light waves refracted by the opposite surfaces of the gasoline film

Answer: the colors come from the interference of light waves reflected from the opposite surfaces of the gasoline film. The correct option is 1.

Explanation:

These bright colours that are constructively produced under sunlight occurs due to interference of light waves reflected from the outer and inner surfaces of the thin layer of gasoline floating on water.

Thin film interference is a natural event that occurs due to reflection of interfered light waves from opposite surfaces of a thin film.

To know whether interference is constructive or destructive, you must determine if there is a phase change upon reflection. Thin film interference depends on.:

- film thickness,

-the wavelength of light, and

- the refractive indices.

For white light incident on a film that varies in thickness, you will observe rainbow colors of constructive interference for various wavelengths as the thickness varies.