Question

Double slit interference experiment is carried out with monochromatic light and interference fringes are observed. If now monochromatic light is replaced by white light; what change is expected in interference pattern?

• A. No change
• B. Pattern disappears
• C. White and dark fringes are observed throughout
• D. A few coloured fringes are observed on either side of central white fringe

Answer 1

Answer: (D)

Central fringe is white because all the wave lengths are super-imposing at central position with maxima. On either sides all wavelengths make their maximas and minimas so they appeared coloured.