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 = 1.26, uniformly covers the top of a glass plate, n = 1.51. 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 both interfaces
at neither interface
air-film
film-glass
omit
Question 2
What is the wavelength of green, 498-nm light as it travels through the film?
330 nm
498 nm
395 nm
627 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?
125 nm
99 nm
249 nm
198 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?
249 nm
198 nm
125 nm
99 nm
omit
Question 5
In general, when green light is removed from white light, the film would appear to be which color?
magenta
grey
cyan
yellow
omit
Question 6
What is the frequency of the green light as it travels through the film?
4.78 x 10
14
hz
1.19 x 10
20
hz
6.02 x 10
14
hz
7.59 x 10
-4
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?
1.67 x 10
-12
sec
1.1 x 10
-12
sec
8.33 x 10
-10
sec
1.83 x 10
-12
sec
1.26 x 10
-9
sec
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