Question

In a Young's double slit experiment, the source is white light. One of the slits is covered by red filter and another by green filter. In this case,

• A. There shall be alternate interference fringes of red and green.
• B. There shall be an interference pattern, where each fringe's pattern center is green and outer edges is red.
• C. There shall be an interference pattern for red distinct from that for green.
• D. There shall be no interference fringes.

Hint:

For interference patterns to form, both slits must emit light of the same wavelength. If different wavelengths are used (such as red and green light), no combined interference pattern will be formed.

Answer 1

The Correct Option is D

In Young's double-slit experiment, the interference pattern is formed when the waves from two slits combine.
When white light passes through two slits, it forms a pattern of colored fringes because the different colors (wavelengths) interfere differently, leading to a spectrum of colors.

Now, if one slit is covered with a red filter and the other with a green filter:
- The red filter allows only red light to pass through the first slit.
- The green filter allows only green light to pass through the second slit.

Since red and green light have different wavelengths, they will produce separate interference patterns.
However, these patterns will not overlap or interfere with each other.
The red light from one slit and the green light from the other will not create a combined interference pattern.

Thus, there will be no interference fringes as expected from a single wavelength of light.
Instead, we see two independent interference patterns for red and green light.

Therefore, the correct answer is Option (4) — There shall be no interference fringes.