Question

How shall a diffraction pattern change when white light is used instead of a monochromatic light?

(a) The pattern will no longer be visible

(b) The shape of the pattern will change from hyperbolic to circular

(c) The colored pattern will be observed with a white bright fringe at the center

(d) The bright and dark fringes will change position

I have been asked this question during an internship interview.

I need to ask this question from Diffraction of Light topic in chapter Diffraction of Engineering Physics II

Answer 1

The correct option is (c) The colored pattern will be observed with a white bright fringe at the center

Explanation: When white light is used instead of monochromatic light, then the central maximum remains white as all seven wavelengths meet there in the same phase. The first minimum and second maximum will be formed by violet color due to its shortest wavelength while the last is due to the red color as it has the longest wavelength. Thus, a colored pattern is observed.

However, after the first few colored bands, the clarity of the band is lost, due to overlapping.