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 = 1.4, uniformly covers the top of a glass plate, n = 1.59. 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
at both interfaces
film-glass
air-film
omit
Question 2
What is the wavelength of blue, 487-nm light as it travels through the film?
306 nm
682 nm
487 nm
348 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?
122 nm
244 nm
87 nm
174 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?
244 nm
87 nm
174 nm
122 nm
omit
Question 5
In general, when blue light is removed from white light, the film would appear to be which color?
yellow
cyan
magneta
grey
omit
Question 6
What is the frequency of the blue light as it travels through the film?
1.04 x 10
20
hz
8.62 x 10
-4
hz
4.4 x 10
14
hz
6.16 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?
1.82 x 10
-12
sec
9.33 x 10
-10
sec
1.48 x 10
-9
sec
1.41 x 10
-12
sec
1.92 x 10
-12
sec
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