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Find angular seperation of spectral lines with a grating spectrometer

  • #1

Homework Statement



find the angular separation between the red hydrogen-alpha spectral line at 656nm and the yellow sodium line at 589nm if the two are observed in third order with a 3500-line/cm grating spectrometer.


Homework Equations


maximum equation for multi-slit interference
d sin(theta)=m*lamda

d=distance between two slits
m=the interger called the order (bright spots)
theta=angular seperation
lamda=wavelength

The Attempt at a Solution



I tried plugging all of my data into the equation above with d as 1/grading but I'm not sure if this is the right way to go about the problem. I'm not even sure if this is the best formula to use but I cant find any other relevant equations
 

Answers and Replies

  • #2
djeitnstine
Gold Member
614
0
Welcome to Pf sailfast

you are correct, your d is 1/3500 to get centimeters per grating. This equation is correct and applies to this problem. Just be careful with your units and 'm'
 
  • #3
yay! i rock at PHYS
 
  • #4
I have the same question here. But when I get sin(theta), I get something over 1. That is not possible. Is my equation wrong? Because I am very sure the units I've been using here are correct. I converted everything into meters.
 

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