(Hindi)Diffraction of light: Fraunhofer Diffraction

Lesson 10 of 17 • 12 upvotes • 13:05mins

Rajesh Kumar

Diffraction of light: the bending of light wave around opening or an obstacle is known as diffraction of light .when light passes through a slit then opening of The slit through which light wave passes then particles between opening behave as secondary wavelets, this wavelets now behave as a source of light wave and these waves interfere at screen. where interference pattern of maxima and minima found this pattern is known as fringe. and this phenomenon is known as diffraction of light .distance between slit and screen is infinite and source of light and difracting element also distance is in Infinity then that special case known as 'fraunhofer diffraction' and when these distance in a finite measurements then that diffraction is known as 'fresnel diffraction. here we discuss about fraunhofer diffraction, width of opening b ,A converging lens and a screen screen is at focus of the converging lens and light waves which come out of opening is now parallels interfere at screen.at p0 on screen Central Maxima at θ= 0,waves from the portion b/2 of opening ,then path difference between waves coming from this opening is Δx = b/2sinθ if path difference is  λ /2, then phase difference between these waves is π. that is the Waves from upper half of the opening is out of phase from lower half of opening. at point P the interference patterns cancel out each other and be observed minimum intensity. maximum intensity found between to minimum intensity .that is for diffraction of light ,opening/ obstacle must be comparable in dimension with respect to wavelength of light.