xLight from a distant, monochromatic source hits an opaque barrier with narrow, parallel slits. Two slits are displaced by distances ±(p/2) from the centerline of the setup. Assume slit spacing p = 0.3 mm, distance d = 9 m to the screen, and visible light with λ = 600 nm.
a) Get a computer to make a graph of light intensity versus screen position x for the two-slit problem.
b) Now consider a new situation: The same light, in the same overall geometry, hits an opaque barrier with three narrow, parallel slits. One slit is at the centerline of the setup; the others are distances ±p from the centerline. Find a formula for the resulting illumination pattern on a distant projection screen, get a computer to graph intensity versus x, and describe in words what it would look like. [Hint: If you wish to drop a term involving p^2, justify doing so.]
c) Consider a third situation: The same light hits an opaque barrier with four narrow, equally-spaced, parallel slits, displaced by distances ±(p/2) and ±3(p/2) from the centerline. Make a third graph. If you see a trend emerging, describe it.
Note that for one slit: ψ = const × e^(i(2πx^2)/(2λR)), R = √(d^2 + x^2)