If red light is replaced by white light then width of diffraction pattern will

Options

A. increase
B. decrease
C. a central white band is obtained
D. no effect.

Explanation

To solve the question regarding the effect of replacing red light with white light on the width of the diffraction pattern, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Diffraction Pattern Formation**:
- A diffraction pattern is formed when light passes through a slit or around an obstacle. The pattern consists of a series of bright and dark fringes.

2. **Identify the Nature of Light**:
- Red light is a monochromatic light source, meaning it consists of a single wavelength (approximately 620-750 nm).
- White light, on the other hand, is not monochromatic; it is composed of multiple wavelengths (the seven colors of the spectrum: red, orange, yellow, green, blue, indigo, violet).

3. **Effect of Wavelength on Diffraction**:
- The width of the diffraction pattern is related to the wavelength of the light used. Generally, a longer wavelength results in a wider diffraction pattern.
- Since white light contains multiple wavelengths, the diffraction pattern will consist of overlapping patterns from all the colors.

4. **Central White Band Formation**:
- When white light is used, the central maximum will appear white because all the colors overlap at the center. However, the fringes on either side will be colored due to the different wavelengths spreading out.

5. **Conclusion**:
- When red light is replaced by white light, the width of the overall diffraction pattern will increase because the different wavelengths will spread out more than a single wavelength (red light).
- Additionally, the central maximum will be white, surrounded by colored fringes.

### Final Answer:
The width of the diffraction pattern will **increase**, and a central white band will be obtained.