Thin films: A coating is being applied to reduce the reflectivity of a pane of glass to light with a frequency of 5.75 × 10¹⁴ Hz that is incident normally on the pane. If the material has an index of refraction of 1.375 and the glass has an index of refraction of 1.537, what is the minimum thickness the coating should have? (c = 3.00 × 10⁸ m/s) A) 60.0 nm B) 94.9 nm C) 145 nm D) 65.2 nm E) 80.1 nm

Question

Quizplus · Accepted Answer

The minimum thickness for destructive interference is given by $ t = \frac{\lambda}{4n} $, where $ \lambda = \frac{c}{f} $. Calculate $ \lambda $ using $ c = 3.00 \times 10^8 $ m/s and $ f = 5.75 \times 10^{14} $ Hz, then use $ n = 1.375 $ for the coating.

Thin Films: a Coating Is Being Applied to Reduce the Reflectivity