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Homework Statement
A mask with 2 slits is illuminated by a light of 589nm wavelength. Slits each have a 0.1mm width separated (centre to centre) by 3.0mm. Calculate the distance between adjacent bright fringes on the screen if a screen is placed 5.0m away from the slits.
Homework Equations
Where
[tex]\beta[/tex]=2[tex]\pi[/tex]dsin[tex]\theta[/tex]/[tex]\lambda[/tex]
[tex]\phi[/tex]=2[tex]\pi[/tex]asin[tex]\theta[/tex]/[tex]\lambda[/tex]
d=slit separation
a=slit width
E=E(max)cos[tex]\frac{\phi}{2}[/tex]*([tex]\frac{sin(\beta/2)}{\beta/2}[/tex])
(sorry, no good with this latex stuff, some stuff not showing right)
The Attempt at a Solution
First, I assume that if given a slit width of some size then we cannot assume that the interference comes from points sources. So to calculate the distance between adjacent bright fringes, I took on the formula for intensity and turned it into electric field of some form (just square rooted) and tried to differentiate the electric field and then find the roots of the equation. However I have found this extremely lengthy and most probably unnecessary. Can anyone get me started in the correct direction?
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