- #1
Zhalfirin88
- 137
- 0
Homework Statement
(a) In a double-slit system, what value of d/a causes diffraction to eliminate the third bright side fringe?
Homework Equations
[tex] I(\theta) = I_mcos^2(\beta)(\frac{sin(\alpha)}{\alpha})^2 [/tex]
[tex] \beta =\frac{\pi d}{\lambda} sin \theta [/tex]
[tex] \alpha = \frac{\pi a}{\lambda} sin \theta [/tex]
[tex] d sin\theta = 3 \lambda [/tex]
[tex] a sin\theta = (3+\frac{1}{2}) \lambda [/tex]
The Attempt at a Solution
I solved for a and d in equations 4 and 5 above and got a ratio of 0.857, which isn't right. I'm not sure really how to go about this, I have a feeling that I need to use equations 2 and 3 but I'm not making the connections.
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