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Bright Fringes (Intro to Quantum Physics Qestion?) 
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#1
Apr2109, 01:24 AM

P: 2

1. The problem statement, all variables and given/known data
The distance between two slits is 0.05mm and the distance to the screen is 2.5m. What is the spacing between the central bright fringe and the firstorder fringe? Use yellow light with a wavelength of 580nm 2. Relevant equations x_{m}=mλL/d 3. The attempt at a solution L=0.5mm d=2.5m λ=580nm x_{m}=(1)(580x10^{9})/(.5x10^{3}) = .00116m (all the numbers were converted to meters) Whenever I plug these problems in, I get a strange answer that isn't anywhere near the multiple choice answers. What am I doing wrong? Multiple choice answer possibilities:
Spoiler
a) 0.01m
b) 0.029m c) 0.29 d) 0.1m e) 0.6m I don't want the answer, I want to know what I did wrong here. If you get the right answer, please help! Cheers, ~a distressed AP student 


#2
Apr2109, 02:12 AM

HW Helper
PF Gold
P: 1,961

Hi megoka,
You mixed up L and d. L is the distance to the screen 2.5 m, and d is the space between the slits 0.05 mm. 


#3
Apr2109, 09:56 AM

P: 2

d=0.5mm L=2.5m λ=580nm
xm=mλL/d x=(1)(580x10^9)(2.5)/(0.5x10^3)=.0029 Okay! Thanks! I got my answer. 


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