Question

In a particular grating, the sodium doublet is viewed in
third order at 10.2° to the normal and is barely resolved.
Find (a) the ruling spacing and (b) the total width of
grating.​

Answer 1

Answer:

ANSWER

(a) From dsinθ=mλ we find

d=

sinθ

mλ

avg

=

sin10

∘

3(589.3nm)

=1.0×10

4

nm=10μm

(b) The total width of the ruling is

L=Nd=(

m

R

)d=

mΔλ

λ

avg

d

=

3(589.59nm−589.00nm)

(589.3nm)(10μm)

=3.3×10

3

μm=3.3mm