What happens to the single slit experiment when the width of the slit is less than wavelength of the waveWhy is diffraction of sound waves more evident (common) than that of light waves?,,We cannot observe the diffraction pattern in a wide slit illuminated by monochromatic light. Why,

What happens to the single slit experiment when the width of the slit is less than wavelength of the wave? 
 
Ans: In single slit experiment, the first central maximum occurs at:

sinθ=λd

Here, λ is the wavelength of light and d is the width of the slit. When the width of slit is less than the wavelength of the wave, the value of λ/d increases. So, diffraction pattern becomes wider.
.
 Why is diffraction of sound waves more evident (common) than that of light waves?
Ans

: We know that the wavelength of sound waves greater that of light waves. For a sustained diffraction, the size of the obstacles should be in the order of wavelength of the waves. The wavelength of sound is comparable to the size of the obstacles around which they bend. But, the wavelength of light is in the order of 10^-6 m and thus cannot be compared with the size of obstacles. So, diffraction of light cannot be observed easily.

. We cannot observe the diffraction pattern in a wide slit illuminated by monochromatic light. Why ?

Ans: We know that the size of central maximum is given by:

2y=2λDa

Where D is the distance between the slits and a is the slit width. So, as the slit width increases, the size of central maximum reduces and diffraction pattern cannot be seen. Even the variation of intensity of other maxima and minima become so small to distinguish. Hence, we cannot observe the diffraction pattern in a wide slit illuminated by monochromatic light.