Question

In a Young's double slit experiment, the source is white light. One slit is covered with red filter and the other with blue filter. There shall be:

• A. alternate red and blue fringes.
• B. alternate dark and pink fringes.
• C. alternate dark and yellow fringes.
• D. no interference.

Answer 1

Answer: (B)

alternate dark and pink fringes.

When the slits of young's double slit experiment is covered with red and blue fringes, the colour will mix where there is constructive interference. Since, red and blue mix to give magenta colour (a shade of pink), the regions of constructive interference will appear as magneta. Regions of destructive interference leads to dark fringe. Hence, the interference pattern will consist of alternate dark and pink fringes.