Question

Why is a diffraction grating better than a two-slit setup for measuring wavelengths of light?

Short answer

The resolving power decrease with a reduction in the number of slits which is why diffraction grating is better than a two-slit setup for measuring the wavelength of light.

Step-by-step solution

Given Data

Diffraction is a process by which a beam of light spreads when passing through a narrow passage or across the edge of an obstacle accompanied by interference between the waveforms.

Diffraction gratings are used in the laboratory to form interference patterns. It has a large number of slits, which produces a very sharp maxima due to which angle of deviation can be measured precisely.

Diffraction grating vs two-slit setup

As we know, the sharpness of maxima depends on the number of slits used in the experiment. As the grating has a large number of parallel equidistant slits of the same width, so the fringes formed by the grating are very sharp. Also, the resolving power decrease with a reduction in the number of slits, which is why diffraction grating is better than two-slit diffraction for measuring of the wavelength of light.