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 = 1.4, uniformly covers the top of a glass plate, n = 1.54. 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
film-glass
air-film
at neither interface
omit
Question 2
What is the wavelength of red, 764-nm light as it travels through the film?
496 nm
1070 nm
764 nm
546 nm
omit
Question 3
At what minimum non-zero thickness of the film will the intensity of the red light reflected back into the air be a maximum?
191 nm
382 nm
136 nm
273 nm
omit
Question 4
At what minimum non-zero thickness of the film will the intensity of the same red light reflected back into the air be a minimum, or experience destructive interference?
273 nm
382 nm
136 nm
191 nm
omit
Question 5
In general, when red light is removed from white light, the film would appear to be which color?
yellow
grey
cyan
magneta
omit
Question 6
What is the frequency of the red light as it travels through the film?
2.8 x 10
14
hz
3.93 x 10
14
hz
1.64 x 10
20
hz
5.5 x 10
-4
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?
9.33 x 10
-10
sec
1.22 x 10
-12
sec
2.01 x 10
-12
sec
1.78 x 10
-12
sec
1.44 x 10
-9
sec
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