Answer:
PART A: 412.98 nm
PART B: 524.92 nm
Explanation:
The equation below can be used for a diffraction grating of nth order image:
n*λ = d*sinθ[tex]_{n}[/tex]
Therefore, for first order images, n = 1 and:
λ = d*sinθ[tex]_{1}[/tex].
The angle θ[tex]_{1}[/tex] can be calculated as follow:
tan θ[tex]_{1}[/tex] = 9.95 cm/15.0 cm = 0.663 and
θ[tex]_{1}[/tex] = [tex]tan^{-1}[/tex] (0.663) = 33.56°
Thus: d =λ/sin θ[tex]_{1}[/tex] = 461/sin 33.56° = 833.97 nm
PART A:
For a position of 8.55 cm:
tan θ[tex]_{1}[/tex] = 8.55 cm/15.0 cm = 0.57 and
θ[tex]_{1}[/tex] = [tex]tan^{-1}[/tex] (0.57) = 29.68°
Therefore:
λ =d*sin θ[tex]_{1}[/tex] = 833.97*sin 29.68° = 412.98 nm
PART B:
For a position of 12.15 cm:
tan θ[tex]_{1}[/tex] = 12.15 cm/15.0 cm = 0.81 and
θ[tex]_{1}[/tex] = [tex]tan^{-1}[/tex] (0.81) = 39.01°
Therefore:
λ =d*sin θ[tex]_{1}[/tex] = 833.97*sin 39.01° = 524.92 nm