Why Do Some Diffraction Orders Go Missing?

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Explain the concept of missing orders in case of double and n slit diffraction.
 
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We say that an order of diffraction is missing if it disappears as a consequence of the overlapping of the interference and the diffraction patterns.

On a screen, intensity from interference has all its maxims at the same level (like a cosine), while intensity for diffraction goes like a sinc (sin(x)/x), so that it gradually tends to 0. The sinc has several zeros (when sin(x)=0 except from x=0), and if one of these zeros overlaps a maximum of interference, we see nothing.
So, there is missing order.

Interference depends on the distance between the slits, while diffraction depends on the width of the slits.

For more info, you can read http://en.wikipedia.org/wiki/Double_slit
 
We say that an order of diffraction is missing if it disappears as a consequence of the overlapping of the interference and the diffraction patterns.

On a screen, intensity from interference has all its maxims at the same level (like a cosine), while intensity for diffraction goes like a sinc (sin(x)/x), so that it gradually tends to 0. The sinc has several zeros (when sin(x)=0 except from x=0), and if one of these zeros overlaps a maximum of interference, we see nothing.
So, there is missing order.

Interference depends on the distance between the slits, while diffraction depends on the width of the slits.

For more info, you can read http://en.wikipedia.org/wiki/Double_slit