Q.What is 'diffraction of light'? Explain its two types.

Diffraction is the spreading of light waves around obstacles; it is classified by whether the wavefronts involved are spherical/cylindrical (Fresnel) or plane (Fraunhofer).

Diffraction of light is the phenomenon of bending of light waves around the corners/edges of small obstacles or apertures, and their consequent spreading into the region of the geometrical shadow. It is a direct consequence of the wave nature of light, occurring significantly when the size of the obstacle/aperture is comparable to the wavelength of light.

Two types of diffraction:

1. Fresnel diffraction: Here, either the source of light or the screen (or both) are at a finite distance from the diffracting obstacle/aperture. As a result, the wavefronts incident on the obstacle are spherical or cylindrical (not plane), and no lenses are required to observe the diffraction pattern — it can be seen directly on a screen placed at a finite distance.

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