In a Young's double slit experiment, the source is white light. One of the slits is covered by red filter and another by a green filter. In this case:
- there shall be alternate interference fringes of red and green.
- there shall be an interference pattern for red distinct from that for green.
- there shall be an interference pattern, where each fringe's pattern center is green and outer edges is red.
- there shall be no interference fringes.
Answer
(4) there shall be no interference fringes.
Solution
A sustained interference pattern needs two coherent sources: same frequency (wavelength) and a constant phase difference.
Light from one slit is red and from the other is green the two waves have different frequencies, so their phase difference changes continuously.
The sources are incoherent; the screen is just uniformly illuminated (red + green) and no interference fringes are seen.
Answer: (4)