Question

Give two differences between Fresnel diffraction and Fraunhofer diffraction.

Answer 1

Hint:
In optics, when the light traveling in a waveform strikes an obstacle or slit, then the light changes its direction and moves around the corners of that obstacle. This phenomenon is known as the “Diffraction.” The amount of the diffraction is directly related to the wavelength of the light, which means that if the wavelength of the light increases, then the amount of diffraction also increases.

There are two types of diffractions-
(1) Fresnel diffraction
(2) Fraunhofer diffraction.

Given:
The two differences between Fresnel diffraction and Fraunhofer diffraction are given by-

Fresnel Diffraction	Fraunhofer Diffraction
1. This type of wave diffraction is observed at the near distance from the obstacle or slit. This diffraction is also known as the Near Field Diffraction.	1. This type of wave diffraction is observed at the far distance from the obstacle or slit. This diffraction is also known as the Far Field Diffraction.
2. The diffraction patterns formed in this type of diffraction change if we move downstream of the diffraction. The shape, as well as the intensity of the diffraction, also changes.	2. The diffraction patterns formed in this type of diffraction do not change, they are constant throughout the pattern and the shape, as well as the intensity of the diffraction, remains constant.

Note:
It should be noted that these diffractions are observed on different types of surfaces. For example, the Fresnel diffraction is observed on the spherical surfaces while the Fraunhofer diffraction is observed on the flat surfaces.