Answer:
[tex]a = 5.7 \times 10^{-5} m[/tex]
Explanation:
As we know that position of first minimum on the either side of central maximum is given as
[tex]a sin\theta = \lambda[/tex]
[tex]\theta =sin^{-1} \frac{\lambda}{a}[/tex]
so the width of the central maximum is given as
[tex]W = L (2\theta)[/tex]
so we have
[tex]15.20 \times 10^{-3} = 0.68 \times 2(sin^{-1} \frac{\lambda}{a})[/tex]
so we have
[tex]0.011 = sin^{-1} \frac{\lambda}{a}[/tex]
[tex]0.011 = \frac{638 nm}{a}[/tex]
[tex]a = 5.7 \times 10^{-5} m[/tex]
