Chapter 25.6, Problem 1aTH

Recall the situation from tutorial, in which light of frequency $f=7.5\times {10}^{14}Hz$ is incident from the left side of a thin soap film $\left(n=\raisebox{1ex}{$4$}\!\left/ \!\raisebox{-1ex}{$3$}\right.\right)$ .

The cross−sectional side view diagram at right extends the ray diagram that you drew in tutorial. It shows the incident ray and several sets of rays resulting from transmission and reflection at the first (left) and second (right) boundaries. The ray that results from the second reflection from the second (right) boundary is not shown.

For the remainder of this problem, assume that the light is incident from the left side of the film at essentially normal incidence.

1. For the two rays that pass through the second boundary and into the air, what are the three smallest film thicknesses for which these rays would:
1. Constructively interfere? Explain.
2. Destructively interfere? Explain.