(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

Three slits of width a and d (separation of adjacent slits). d << the distance to the screen. Show that the intensity we observe is

[tex]I (\vartheta) = I_{1} \left[1 + 2 cos \left(\frac{2 \pi d sin\vartheta}{\lambda} ) \right] ^{2}[/tex]

2. The attempt at a solution

For an angle [tex]\vartheta[/tex] we see that the waves from slit 1 and 3 must travel a distance dsin[tex]\vartheta[/tex] shorter and longer than the waves from slit 2 to get to a point on the screen.

Total wave amplitude far from the slits:

A = A1 + A2 + A3 = [tex] A _{0}sin(kx - \omega t - \varphi )+ A _{0}sin(kx - \omega t) + A _{0}sin(kx - \omega t + \varphi )[/tex]

Am I on the right track? How do I find an easier expression for A?

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# Homework Help: Triple slit interference

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