Show that a grating made up of alternately transparent and opaque strips of equal width eliminates all the even orders of maxima (except ).
It is proved that a grating made up of alternately transparent andopaque strips of equal width eliminates all the even orders of maximaexcept .
There is a grating made up of alternately transparent andopaque strips of equal width.
The angular distance of the order diffraction maxima produced from a grating having line separation is
Here, is the wavelength of the incident light.
The angular distance of the order single slit diffraction minima for slit width is
Slit separation is the distance between the mid points of two slits. Hence slit separation is equal to twice the slit width, that is
Thus, equation (1) becomes
Subtract twice of equation (2) from equation (3) to get
Thus the even order grating diffraction maxima’s (except ) overlap with single slit diffraction minima’s and disappear.
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