Phasor Diagram for Eight Slits an interference pattern is produced by eight equally spaced, narrow slits. Figure 36.14 shows phasor diagrams for the cases in which the phase difference Φ between light from adjacent slits is Φ = π, Φ = π/4, and Φ = π/2. Each of these cases gives an intensity minimum. The caption for Fig. 36.14 also claims that minima occur for Φ = 3π/4, Φ = 5π/4, Φ π = 3π/2, and Φ = 7π/4.
(a) Draw the phasor diagram for each of these four cases, and explain why each diagram proves that there is in fact a minimum.
(b) For each of the four cases Φ = 3π/4, Φ = 5π/4, Φs = 3π/2, and Φ = 7π/4, for which pairs of slits is there totally destructive interference?