hair pin interference problem.

[SaintJude]

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http://imgur.com/SblKU

I& III correct but I am mostly concerned for no.2.

Here is the solution on why Statement II is wrong. And I don't understand the claims in italics.

Filling the gap with carbon disulfide, as opposed to air, would lead to a smaller difference between the index of refraction of the medium and that of the glass. A smaller difference in n values results in less bending of light as it passes from one medium into the next, so the light would need to travel farther to get the same maxima as it got when air filled the gap. This would spread the bright spots, thereby increasing the distance between adjacent maxima. Statement II is invalid.

 

[MedPR]

http://imgur.com/SblKU

I& III correct but I am mostly concerned for no.2.

Here is the solution on why Statement II is wrong. And I don't understand the claims in italics.

Filling the gap with carbon disulfide, as opposed to air, would lead to a smaller difference between the index of refraction of the medium and that of the glass. A smaller difference in n values results in less bending of light as it passes from one medium into the next, so the light would need to travel farther to get the same maxima as it got when air filled the gap. This would spread the bright spots, thereby increasing the distance between adjacent maxima. Statement II is invalid.

Yea there's another thread about this where people were asking the same question. I was explaining it when about midway through my paragraph I realized that what I was saying made no sense. I don't understand the explanation either.

 

[MrNeuro]

yeah im 99.9999% sure they're wrong

http://forums.studentdoctor.net/showthread.php?t=686488

 

[milski]

Interesting. There is a derivation in my physics textbook of how many stripes per cm are observed. It makes them dependent on the angle between the two slides and the wavelength of the ray but ignores the refraction index of the media. From that point of view answer 2 would be incorrect. At most you're going to switch dark and bright spots if you go from no phase change to π phase change.

The explanation about smaller difference between refraction indices also makes sense. The light will bend a bit less and will follow slightly shorter path between the two slides. I don't know if the difference is significant enough to be taken into account but however bit it is, it is in the wrong direction.

 

[MrNeuro]

Interesting. There is a derivation in my physics textbook of how many stripes per cm are observed. It makes them dependent on the angle between the two slides and the wavelength of the ray but ignores the refraction index of the media. From that point of view answer 2 would be incorrect. At most you're going to switch dark and bright spots if you go from no phase change to π phase change.

The explanation about smaller difference between refraction indices also makes sense. The light will bend a bit less and will follow slightly shorter path between the two slides. I don't know if the difference is significant enough to be taken into account but however bit it is, it is in the wrong direction.

how does that make sense??? if the angle of refraction is greater the light will refract towards the normal yielding a smaller path length if the angle of refraction is smaller it will refract away from the normal yielding a longer path length....HELP ME MILSKI

 

[milski]

Consider the light between the slides (the slides are the darker green area). If the index of refraction is closer to that of the slides the light will be more "vertical" and will return to the upper slide closer to where it left it. That's the same thing as bringing the slides closer - shortening the path.