Physics
Wave Optics Solutions
JA observer
incident
ray
A transparent glass plate with a refractive index ng = 1.3 is
coated with a thin film of refractive index ng = 1.4. This
film is meant to reduce the glare of reflected light (like an
anti-reflective coating on eye-glasses). Monochromatic
(single color) light, with a wavelength 2, is incident on the
film as shown, and a reflection is not seen by the observer.
a) [5 points] Explain, in a coherent paragraph, the
conditions for which the observer would not see the
orange light. On the diagram, sketch what happens to
the incident ray to support your explanation.
air (n = 1)
film (n=1.4)
glass (n = 1.3)
b) [5 points) The thickness of the film is 250 nm. For this thickness, what color(s) of light, if
any, will not be reflected? What color(s), if any, will be strongly reflected? Show your work
and explain your reasoning. Note: Wavelengths of the visible spectrum are given/discussed on
the coversheet.
