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

Step-by-step 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.