Question:
A glass surface is coated by an oil film of uniform thickness $1.00 \times 10^{-4} \mathrm{~cm}$. The index of refraction of the oil is $1.25$ and that of the glass is $1.50$. Find the wavelengths of light in the visible region ( $400 \mathrm{~nm}-750 \mathrm{~nm}$ ) which are completely transmitted by the oil film under normal incidence.
Solution:
