## Multi-slit Interference - Phasor method for N slits

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.]