duction When two or more light waves pass through a given point, their electric fields combine according to the principle of linear superposition and produce a resultant electric field. The square of the electric field strength is proportional to the intensity of the light, which, in turn, is related to its brightness. IE^2 When two identical waves arrive in phase, then the waves reinforce each other, and constructive interference occurs. When two identical waves arrive out of phase with one another, or crest-to-trough. Then they cancel each other, and, and destructive interference results. Diffraction is the bending of waves around obstacles or the edges of an opening. Diffraction patterns of bright and dark fringes occur when monochromatic light passes through a single or double slit or a diffraction grating. The angular position with respect to the center can be determined using the Principal maxima of a diffraction grating: sin_m=m/d Where m is the order, is the light wavelength, and d is the distance between slits in the diffraction grating. In the diffraction experiment, the angular position (_m) can be determined using the distance between diffraction grating and the screen (L) and location of the maxima on the screen with