# Slit & light interference

by quicksilver123
Tags: interference, light, slit
 P: 91 1. The problem statement, all variables and given/known data Two narrow slits are cut into a sheet of paper and set in front of a laser beam, causing an interference pattern to appear on the wall. If the distance from one slit to the third bright fringe is 0.5000004 m and the distance from the other slit to the same bright fringe is 0.5000008 m calculate the wavelength of the light from the laser. 2. Relevant equations | PmS1 - PmS2 |= m$\lambda$ 3. The attempt at a solution My answer: |0.5000004-0.5000008|=(3)$\lambda$ 0.0000004/3 = $\lambda$ $\lambda$ = 0.000000133 m edit: my answer uses | P3S1 - P3S2| whereas the book's answer uses | PmS1 - PmS2| How would I turn one into the other? The book's answer: |0.50000030-0.50000165|=3$\lambda$ $\lambda$=0.00000135/3 $\lambda$=0.00000045m = 450nm I'd like to know where they got the values of: PmS1=0.50000030m and PmS2=0.50000165m
HW Helper
Thanks
PF Gold
P: 4,887
 Quote by quicksilver123 If the distance from one slit to the third bright fringe is 0.000004 m and the distance from the other slit to the same bright fringe is 0.000008 m
Did you leave out the "5" after the decimal points? Your work looks correct to me. I don't see where the book's numbers come from either.
 P: 91 didn's leave anything out :/ sorry, i edited my original post a second ago. edit: my answer uses | P3S1 - P3S2| whereas the book's answer uses | PmS1 - PmS2| How would I turn one into the other?
HW Helper
Thanks
PF Gold
P: 4,887
Slit & light interference

 Quote by quicksilver123 didn's leave anything out :/ sorry, i edited my original post a second ago.
Is the distance from the first slit to the bright fringe 0.000004 m or 0.500004 m?

 edit: my answer uses | P3S1 - P3S2| whereas the book's answer uses | PmS1 - PmS2| How would I turn one into the other?
Let m = 3?
 P: 91 sorry, corrected the mistake. the book has been known to make errors in their solutions... but i was wondering if there's something i'm missing
 HW Helper Thanks PF Gold P: 4,887 I think your work is correct.
 P: 91 alright, thanks

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