Imagine that you have an opaque screen with three horizontal very narrow parallel slits in it. The second slit is a center-to-center distance a beneath the first, and the third is a distance 5α/2 beneath the first. (a) Write a complex exponential expression in terms of δ for the amplitude of the electric field at some point-P at an elevation θ on a distant screen where δ = kα sin θ. Prove that

Verify that at θ = 0, I(θ) = I(0).

I(0), 21(0) (cos 8 + cos 38/2 + cos 58/2) 1() 3