Practice Problems
Thin Film Interference Glass Coating
Directions:
On this worksheet you will be investigating the basic properties of
thin film interference
.
omit
Question 1
A thin film, n = 1.25, uniformly covers the top of a glass plate, n = 1.5. 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?
air-film
at both interfaces
film-glass
at neither interface
omit
Question 2
What is the wavelength of blue, 469-nm light as it travels through the film?
375 nm
469 nm
313 nm
586 nm
omit
Question 3
At what minimum non-zero thickness of the film will the intensity of the blue light reflected back into the air be a maximum?
235 nm
94 nm
188 nm
117 nm
omit
Question 4
At what minimum non-zero thickness of the film will the intensity of the same blue light reflected back into the air be a minimum, or experience destructive interference?
117 nm
235 nm
94 nm
188 nm
omit
Question 5
In general, when blue light is removed from white light, the film would appear to be which color?
grey
cyan
magneta
yellow
omit
Question 6
What is the frequency of the blue light as it travels through the film?
6.4 x 10
14
hz
8 x 10
-4
hz
5.12 x 10
14
hz
1.13 x 10
20
hz
omit
Question 7
If the glass plate is 25 centimeters thick, how many seconds would be required for the transmitted beam to travel through the glass?
1.16 x 10
-12
sec
8.33 x 10
-10
sec
1.47 x 10
-12
sec
1.78 x 10
-12
sec
1.25 x 10
-9
sec
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