A person views the interference pattern, produced by two slits illuminated by white light, on placing a green filter in front of his eyes. Then

Options

A. He will see sharply distinguishable dark and bright fringes
B. The fringes will not be sharp but are differentiable
C. On replacing the green filter by a blue filter, the fringes will be again sharp bul closer than those by the green filter
D. On using both the filters simultaneously, the central bands will be maximum bright

Answer

To solve the question regarding the effect of placing a green filter in front of the eyes while viewing an interference pattern produced by two slits illuminated by white light, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding White Light and Interference**:
- White light is composed of multiple colors (Violet, Indigo, Blue, Green, Yellow, Orange, Red - VIBGYOR), each having different wavelengths.
- When white light passes through two slits, it creates an interference pattern on the screen, where different colors overlap and combine to form a bright white fringe at the center (central maximum) due to constructive interference.

2. **Effect of the Green Filter**:
- When a green filter is placed in front of the observer's eyes, it allows only green light to pass through while blocking other colors.
- As a result, the observer will only see the interference pattern created by the green light.

3. **Observation of Fringes**:
- With the green filter, the central maximum will still be visible, but it will appear as a bright green fringe.
- The fringes will be more sharply distinguished because the other colors are filtered out, reducing the overlapping of different wavelengths that would normally create a more blended appearance.

4. **Sharpness of Fringes**:
- The sharpness of the fringes increases because the interference pattern is now primarily due to one wavelength (green), leading to clearer dark and bright fringes.
- The minima (dark fringes) will be more pronounced as the other colors that would contribute to the brightness at those points are blocked.

5. **Comparison with Other Filters**:
- If a blue filter is used instead of a green filter, the same principle applies. The fringes will also be sharp, but they will be closer together than those seen with the green filter due to the shorter wavelength of blue light compared to green light.

6. **Conclusion**:
- Therefore, the correct observations when using a green filter are that the observer will see sharply distinguished dark and bright fringes, and if a blue filter is used instead, the fringes will be sharp but closer together than those produced by the green filter.

### Final Answer:
- The correct options are:
1. The observer will see sharply distinguished dark and bright fringes.
2. If a blue filter is used, the fringes will be sharp but closer than those by the green filter.