Practice Problems
Thin Film Interference Glass Coating
Directions:
On this worksheet you will be investigating the basic properties of
thin film interference
revealed in different thicknesses film on glass.
omit
Question 1
A thin film, n = 1.38, uniformly covers the top of a glass plate, n = 1.6. If the medium above the film is air, at which of the interfaces (air-film and film-glass) does the light undergo a 180° phase change upon reflection?
at neither interface
film-glass
air-film
at both interfaces
omit
Question 2
What is the wavelength of green, 556-nm light as it travels through the film?
348 nm
556 nm
767 nm
403 nm
omit
Question 3
At what minimum non-zero thickness of the film will the intensity of the green light reflected back into the air be a maximum?
201 nm
139 nm
101 nm
278 nm
omit
Question 4
At what minimum non-zero thickness of the film will the intensity of the same green light reflected back into the air be a minimum, or experience destructive interference?
278 nm
201 nm
139 nm
101 nm
omit
Question 5
In general, when green light is removed from white light, the film would appear to be which color?
grey
magenta
cyan
yellow
omit
Question 6
What is the frequency of the green light as it travels through the film?
1.21 x 10
20
hz
5.4 x 10
14
hz
7.45 x 10
-4
hz
3.91 x 10
14
hz
omit
Question 7
If the glass plate is 28 centimeters thick, how many seconds would be required for the transmitted beam to travel through the glass?
1.49 x 10
-9
sec
9.33 x 10
-10
sec
1.96 x 10
-12
sec
1.39 x 10
-12
sec
1.68 x 10
-12
sec
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