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 = 1.26, uniformly covers the top of a glass plate, n = 1.56. 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
air-film
film-glass
at both interfaces
omit
Question 2
What is the wavelength of blue, 481-nm light as it travels through the film?
308 nm
481 nm
606 nm
382 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?
191 nm
95 nm
120 nm
241 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?
241 nm
120 nm
191 nm
95 nm
omit
Question 5
In general, when blue light is removed from white light, the film would appear to be which color?
cyan
yellow
magneta
grey
omit
Question 6
What is the frequency of the blue light as it travels through the film?
1.15 x 10
20
hz
7.86 x 10
-4
hz
6.24 x 10
14
hz
4.95 x 10
14
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?
1.3 x 10
-9
sec
1.26 x 10
-12
sec
1.73 x 10
-12
sec
8.33 x 10
-10
sec
1.46 x 10
-12
sec
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