The colours seen in the reflected white light from a thin oil film are due to

Options

A. Diffraction
B. Interference
C. Polarisation
D. Dispersion

Explanation

To answer the question about the colors seen in the reflected white light from a thin oil film, we can break down the explanation into clear steps:

### Step-by-Step Solution:

1. **Understanding Thin Oil Films**: When a thin layer of oil is spread over a surface (like water or a road), it creates a film that can reflect light. This film is typically very thin, on the order of wavelengths of light.

2. **White Light and Its Composition**: White light is made up of various colors, which can be separated into a spectrum (like a rainbow) when passed through a medium or reflected off surfaces.

3. **Interference of Light**: The colors observed in the reflection from the oil film are due to the phenomenon of interference. When light waves reflect off the top and bottom surfaces of the thin oil film, they can combine in different ways.

4. **Constructive and Destructive Interference**:
- **Constructive Interference** occurs when the light waves from the two surfaces are in phase (their peaks align), resulting in increased brightness for certain colors.
- **Destructive Interference** occurs when the light waves are out of phase (the peak of one wave aligns with the trough of another), resulting in reduced brightness or cancellation of certain colors.

5. **Color Formation**: The specific colors that are seen depend on the thickness of the oil film and the angle of incidence of the light. Different wavelengths (colors) of light will interfere constructively or destructively based on these factors, leading to the appearance of a spectrum of colors.

6. **Conclusion**: The colors seen in the reflected white light from a thin oil film are primarily due to the interference of light waves reflecting from the different surfaces of the film. This interference results in a combination of constructive and destructive interference, producing the vibrant colors observed.