Question
Describe the main difference between Fraunhofer and Fresnel's diffraction.
✓
Answer
There are following differences between these two :
| S.No. | Fraunhofer Diffraction | Fresnel Diffraction |
| 1. | The center of the diffraction pattern is always bright. | The center of the diffraction pattern is sometimes bright and sometimes dark. |
| 2. | Both the source and the screen are located at an effectively or actually infinite distance from the diffractor. | Both the source and the screen are at a limited distance from the diffractor |
| 3. | Wave fronts are plane. | Wave fronts are spherical or cylindrical. |
| 4. | Convex lens is used in this. | Convex lenses are not used in this. |
| 5. | There may be a combined effect of diffraction of more than one diffractor. | In this there is diffraction effect of only one diffractor. |
| 6. | Its theoretical analysis is done with the help of adequate and precise mathematics. | Its theoretical analysis is complex and gives only approximate values. |
| 7. | In this type of diffraction, the inclination of the wave fronts towards the diffractor is important. | In this diffraction, the distances of the source and the screen from the diffractor are important. |
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