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Double slit 
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#1
Dec907, 11:17 PM

P: 12

1. The problem statement, all variables and given/known data
A laser with wavelength d/8 is shining light on a double slit with slit separation d. This results in an interference pattern on a screen a distance L away from the slits. We wish to shine a second laser, with a different wavelength, through the same slits. What is the wavelength (lambda_2) of the second laser that would place its second maximum at the same location as the fourth minimum of the first laser? Express your answer in terms of d 2. Relevant equations I have (dsin(theta)) = 2(lambda_1) and dsin(theta)= (9/2)(lambda_2) 3. The attempt at a solution I set the two equations equal to each other, and solve for lambda_2 and get (2/9)dsin(theta), but then it said the answer does not depend on theta.. so I just guessed and put (2/9)d and it said I was off by a multiplicative factor. basically, I'm confused and do not know how to go about solving this problem. please help! 


#2
Dec1007, 12:06 AM

HW Helper
P: 4,435

I have (dsin(theta)) = 2(lambda_1)
and dsin(theta)= (9/2)(lambda_2) Check this. Second maximum of second laser and fourth minimum of the first laser 


#3
Dec1007, 12:44 AM

P: 12

is it
(2(lambda_2)L)/d = ((4+.5)(d/8)L)/d 


#4
Dec1007, 12:54 AM

HW Helper
P: 4,435

Double slit
Yes.



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