Multi-slit Interference - Phasor method for N slits

Number of slits (n>=2) =    
Phase angle (deg) =        

You can select the number of slits, each containing an Electric field vector, and then vary the phase angle between each of the vectors. The phasor method puts the vectors head to tail, and vectorially adds the x components and y components. The screen on the left shows the graphical version of the vectors adding together. The screen on the right shows the intensity pattern for that N-slit pattern, and a data point indicating the particular phase angle chosen on the left. Note : the initial vectors are "scaled down" based on the number of slits .. so that they will fit on the screen to the left. Notice as the number of slits rises ... the peak intensties grow (as a function of n*n) and the peaks themselves get more narrow. Thus, diffraction gratings have very tall and very narrow peaks (dots, instead of "dashes" as with 2 slits). [In Internet Explorer .. the vectors sometimes disappear .. I'm not sure why .. try changing the angle by 1 degree to see them again.]