Snell's Law

\( \frac{n_1}{n_2} = \frac{sin \theta_2 }{sin \theta_1 } = \frac{v_2}{v_1} \)

Constructive interference:

path difference = nλ

Deconstructive interference:

path difference = (n + ½)λ

\( s = \frac{ \lambda D }{d} \)

\( \theta = \frac{ \lambda }{b} \)

nλ = dsinθ