Diffraction refers to various phenomena which occur when a wave encounters an obstacle or a slit. In classical physics, the diffraction phenomenon is described as the interference of waves according the Huygens Fresnel principle. These characteristic behaviors are exhibited when a wave encounters an obstacle or a slit that is comparable in size to its wavelength.
Diffraction can be expressed as:
xm ≈ mλL/d
xm = The position
m = number times
λ = wavelength (λ) times
L =distance (L)
d = the separation (d).