1)An oil film on water appears brightest at the outer regions, where it is thinnest. from this information, what can you say about the index of refraction of oil relative to that of water.
2)Why two flashlights held close together do not produce an interference pattern on a distant screen?
3)If a fine wire is stretched across the path of a laser beam, is it possible to produce a diffraction pattern?© BrainMass Inc. brainmass.com October 24, 2018, 7:50 pm ad1c9bdddf
1) Since it is brightest at the outer region, constructive interference occurs there, so the index of refraction of oil would be lower than that of water. If it were larger, the two reflections would be out of phase and interfere ...
The solution explains concepts of refraction, interference and diffraction and how they are applied to oil films, flashlights and a laser beam.
Figuring thickness of gasoline floating on a puddle of water with sunlight reflecting off of it.
Question 2 (10 points)
A thin film of gasoline floats on a puddle of water. Sunlight falls almost perpendicularly on the thin film and reflects to your eyes. Although the sunlight is white, and it contains all colors, the film has a yellow hue because of destructive interference eliminating the color blue. Blue wavelength = 469 nm. If the refractive index of blue light in gasoline is 1.40 and blue light in water is 1.33, determine the minimum thickness of the film for this to occur.
a. 168 nanometers
b. 1.34 micrometers
c. 10.3 Angstrom units
d. 12.24 millimeters
e. 4 nanometers
If I have solved this correctly, I am coming up with:D = (m + ½) λo / 2nf 164.15 nm = (0 + ½)(469nanometers)/ 2(1.40)Am I close enough or correct to use (a.) 168 nm?
Question 3 (10 points)
A thin film of gasoline coats a flat piece of glass. Sunlight falls almost perpendicularly on the thin film and reflects to your eyes. Although the sunlight is white, and it contains all colors, the film has a yellow hue because of destructive interference eliminating the color blue. Blue wavelength = 469 nm. If the refractive index of blue light in gasoline is 1.40 and blue light in the glass is 1.52, determine the minimum thickness of the film of gasoline for this to occur. With this problem, If I am correct,
a. 838 Angstroms
b. 1,345 Angstroms
c. 2,334 Angstroms
d. 5,055 Angstroms
e. 14,331 Angstroms
I am using:Dmin = mλo/2nf167.5 nm = m(469)/2(1.40)If I use 1 for "m" If I use the formula:λo = 2nfd/m460.6 nm or 4606 Angstroms = 2(1.40)(164.5nm)/mAgain, if I use 1 for "m"If I use the 168 nm from the above problem, I get:λo = 2nfd/m470.4 nm or 4704 Angstroms = 2(1.40)(168nm)/mAgain, if I use 1 for "m"This answer corresponds closer to the 469 nm for the Blue wavelength.If I use 2 for "m", I get 235.2 nm or 2352 Angstroms, which is closer to answer(c.) of 2334 Angstroms.Can you please help me out on this? Thank you.
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