Fresnel diffraction is produced due to light rays falling on a small obstacle. The intensity of light at a…
Fresnel diffraction is produced due to light rays falling on a small obstacle. The intensity of light at a point on a screen beyond an obstacle depends on
the focal length of lens used for observation
the number of half-period zones that superpose at the point
the square of the sum of the number of half period zones
the thickness of the obstacle
Solution
In Fresnel diffraction, no lenses are required for rendering light rays parallel and also the diffraction pattern may be dark or bright depending upon the number of half-period zones that superpose at the point. Hence, the intensity of light at a point a screen beyond or obstacle depends on the number of half-periods zones that superpose at the point.