SOMEONE PLSSSS HELP ME WITH THIS QUESTION!!

λ = 1.90 10⁻⁶ m

Explanation:

The interference pattern for the two-slit case is

          d sin θ = m λ

let's use trigonometry

         tan θ = y / L

interference experiments angles are small

        tan θ = sin θ /cos θ = sin θ

        sin θ = y / L

we substitute

       d y / L = m λ

       λ =

we calculate

       λ = 0.2000 10⁻³ 9.49 10⁻³ / (1  1.00)

       λ = 1.898 10⁻⁶ m

       λ = 1.90 10⁻⁶ m