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
at neither interface
at both interfaces
soap-air
omit
Question 2
What is the wavelength of green, 561-nm light as it travels through the film?
407 nm
774 nm
561 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?
140 nm
281 nm
203 nm
102 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?
102 nm
281 nm
140 nm
203 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
grey
cyan
omit
Question 6
What is the frequency of the green light as it travels through the soap film?
3.88 x 10
14
hz
5.35 x 10
14
hz
7.38 x 10
-4
hz
1.22 x 10
20
hz
omit
Question 7
If the soap film were instead specified to be 606 nanometers thick, which wavelength in the visible spectrum would be canceled?
8.78 x 10
2
nm
1.21 x 10
3
nm
1.67 x 10
3
nm
4.18 x 10
2
nm
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