Diffraction of light:- “the phenomenon of bending of light around the sharp corners of an obstacle and spreading into the geometrical should is called diffraction of light.”

Note:-

1. Diffraction occurs when the size of obstacle is comparable to wavelength of light.
2. Minimum distance of observer from the obstacle to observe the diffraction of light is     ,  d=> size of light source ,  λ=> wavelength of light used to illuminate the obstacle.
3. Fresnel distance : distance of screen from slit when spreading of light due to diffraction from the centre of screen is equal to width of slit
4.