Answer:
λ = 2042 nm
Explanation:
given data
screen distance d = 11 m
spot s = 4.5 cm = 4.5 ×[tex]10^{-2}[/tex] m
separation L = 0.5 mm = 0.5 ×[tex]10^{-3}[/tex] m
to find out
what is λ
solution
we will find first angle between first max and central bright
that is tan θ = s/d
tan θ = 4.5 ×[tex]10^{-2}[/tex] / 11
θ = 0.234
and we know diffraction grating for max
L sinθ = mλ
here we know m = 1 so put all value and find λ
L sinθ = mλ
0.5 ×[tex]10^{-3}[/tex] sin(0.234) = 1 λ
λ = 2042.02 ×[tex]10^{-9}[/tex] m
λ = 2042 nm
