Practice Problems
Thin Film Interference Soap Bubbles
Directions:
On this worksheet you will be investigating the basic properties of
thin film interference
.
omit
Question 1
A thin soap bubble, n = 1.38, is filled with air. Since the medium outside the bubble is also air, at which of the interfaces (air-soap and soap-air) would the light undergo a 180° phase change upon reflection?
air-soap
soap-air
at neither interface
at both interfaces
omit
Question 2
What is the wavelength of green, 521-nm light as it travels through the film?
521 nm
719 nm
378 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?
130 nm
94 nm
261 nm
189 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?
261 nm
130 nm
94 nm
189 nm
omit
Question 5
In general, when green light is removed from white light, the soap bubble would appear to be which color?
magenta
yellow
cyan
grey
omit
Question 6
What is the frequency of the green light as it travels through the soap film?
4.17 x 10
14
hz
5.76 x 10
14
hz
1.13 x 10
20
hz
7.95 x 10
-4
hz
omit
Question 7
If the soap film were instead specified to be 591 nanometers thick, which wavelength in the visible spectrum would be canceled?
1.18 x 10
3
nm
4.08 x 10
2
nm
8.57 x 10
2
nm
1.63 x 10
3
nm
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