Chapter 24, Problem 18Q

To determine

Difference in the interference pattern formed by two slits and by a diffraction grating.

Explanation of Solution

Introduction:

Young’s double slit experiment depicts the wave theory of light by the observation of the interference pattern.

A diffraction grating can be defined as a large number of slits which are equally spaced. Diffraction grating can be divided in two types: transmission and reflection grating.

When a monochromatic light is passing through the slits having distance ${10}^{-4}\text{cm}$ from each other, then a pattern of dark and bright fringes is observed. The interference pattern so formed is due to the overlapping of the light waves.In case of interference pattern formed by a diffraction grating that contains ${10}^4\text{lines/cm}$ , can have a sharply defined maxima as well as more narrow than the interference pattern formed by the two slits.

Conclusion:

Hence, the interference pattern so formed by the two slits ${10}^{-4}\text{cm}$ apart is less narrow. While the interference pattern formed by a diffraction grating has a sharply defined maxima.