The correct formula for the double-slit experiment is given by
[tex]y= \frac{n \lambda D}{d} [/tex]
where
y is the distance of the n-th maximum from the central fringe on the screen
n is the order of the maximum
D is the distance between the slits and the screen
d is the distance between the two slits
In our problem, we are given:
[tex]\lambda=576.3 \cdot 10^{-9} m[/tex], the wavelength of the light
[tex]D=8.85m[/tex], the distance of the screen from the slits
[tex]y_1 = 5.36 cm = 0.0536 m[/tex] is the distance of the first maximum (n=1) from the central fringe
Therefore, we can re-arrange the equation to calculate the separation between the slits:
[tex]d= \frac{n \lambda D}{y_n}= \frac{(1)(576.3 \cdot 10^{-9} m)(8.85 m)}{0.0536 m}=9.52 \cdot 10^{-5} m [/tex]
