Answer:
560nm
Explanation:
You can use the following expression for thin films:
[tex]\lambda=\frac{2nd}{m}[/tex]
where n is the index of refraction, d is the thicknes of the thin film and m is the order of the diffraction pattern. For keratin layers we can use n=1.40. For the longest wavelenth we use m =1.
Hence, we obtain:
[tex]\lambda=\frac{2(1.40)(200nm)}{1}=560nm[/tex]
HOPE THIS HELPS!!