# Missing Orders in Diffraction

1. Sep 4, 2011

### prashant07

Explain the concept of missing orders in case of double and n slit diffraction.

2. Sep 4, 2011

### DiracRules

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.

3. Sep 4, 2011

### DiracRules

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.