Answer: λ = 5.41×10^-7 m
Explanation: The formulae that defines a double slit interference experiment is given as
mλ = d×sinθ
from the question,
d = distance between slits = 2.9×10^-6.
m = 1 (since interference occurred at the first order)
θ = 12°
λ=?
By substituting the parameters into the formulae, we have that
1 * λ = 2.9×10^-6 * sin 12°
λ = 2.9×10^-6 * 0.2079
λ = 0.541×10^-6
λ = 5.41×10^-7 m
