Question

Name the phenomenon which is responsible for bending of light around sharp corners of an obstacle. Under what conditions does this phenomenon take place?

Answer 1

Hint:There are many phenomena which are in relation with light. Try to recall them and the phenomenon responsible for bending of light around sharp corners of an obstacle (obstacle can be any object which resists light to go straight in that direction) is diffraction.

Complete step by step answer:Diffraction is responsible for bending of light around sharp corners of an obstacle.
There are two types of diffraction
(1) Fraunhofer diffraction
In Fraunhofer diffraction, source and the screen are far apart from each other. Diffracting obstacles on the incident wave fronts are planes. Diffracting obstacles give rise to plane wave fronts. Plane diffraction wavefronts are converged by means of a convex lens in order to produce a diffraction pattern.
(2) Fresnel diffraction
In Fresnel diffraction, light from a point source meets an obstacle and a pattern is observed and the pattern observed is a fringed image of the object. Here, waves are spherical in nature. Wave fronts leaving the obstacle are also spherical. Here, no convex lens is needed to converge the spherical wave fronts.
The cause of diffraction is the shifting of waves by any diffracting object and this shift causes the wave to have interference with itself.
Essential condition for diffraction to occur is as follows:
The size of the obstacle should not be too large or too small. It should be comparable to the wavelength of the light.

Note:The term diffraction and interference closely related phenomena. In simper term, diffraction can be considered interference with scattering. Interference is the phenomenon of superimposing of waves to produce a resultant wave of greater, lower, or the same amplitude.