- Joined
- Nov 12, 2008
- Messages
- 240
- Reaction score
- 2
This is example 10.9b in the BR physics books.
A thin hair is placed between two microscope slides. When laser light is shined down onto the slides, periodic intensity maxima are seen to span the slides. Which of the following changes will decrease the distance between the maxima?
I. Decrease the wavelength of the laser light.
II. Fill the air gap between the slides with carbon disulfide (n=1.6)
III. Move the hair to the left, while keeping the slides in contact with each other at their left edges.
The correct answer is I and III.
I'm pretty much clueless about everything here- what equations are necessary for this problem?
This is as far as my reasoning goes:
We are observing the reflected light rays off of the bottom layer of the top microscope slide (which doesn't have a phase change) and the reflected light rays off of the top of the bottom microscope slide (which DOES have a phase change). Thus for constructive interference 2d= m+0.5 (wavelength/n) where n is the index of refraction and m is any integer and d is the gap of air between the two slides. I'm entirely confused, though, as to how to determine the distance between the maxima- any help would be greatly appreciated.
A thin hair is placed between two microscope slides. When laser light is shined down onto the slides, periodic intensity maxima are seen to span the slides. Which of the following changes will decrease the distance between the maxima?
I. Decrease the wavelength of the laser light.
II. Fill the air gap between the slides with carbon disulfide (n=1.6)
III. Move the hair to the left, while keeping the slides in contact with each other at their left edges.
The correct answer is I and III.
I'm pretty much clueless about everything here- what equations are necessary for this problem?
This is as far as my reasoning goes:
We are observing the reflected light rays off of the bottom layer of the top microscope slide (which doesn't have a phase change) and the reflected light rays off of the top of the bottom microscope slide (which DOES have a phase change). Thus for constructive interference 2d= m+0.5 (wavelength/n) where n is the index of refraction and m is any integer and d is the gap of air between the two slides. I'm entirely confused, though, as to how to determine the distance between the maxima- any help would be greatly appreciated.