**Answer:**

λ₀= 495.88 nm

**Explanation:**

To analyze this constructive interference interference experiment by reflection, let's look at two important aspects:

* when a ray of light passes from a medium with a lower index, they refact to another medium with a higher index, the reflected ray has a phase difference of pyres

* When a beam penetrates a material medium, the wavelength of the radiation changes according to the refractive index of the material.

λₙ = λ₀ / n

when we introduce these aspects in the expression of contributory interference, it remains

2 d sin θ = (m + ½) λ₀ / n

In general, reflection phenomena are measured at an almost normal angle, whereby θ = π/2 and sin θ = 1

2 d = (m +1/2) λ₀/ n

2n d = (m + ½) λ₀

Let's apply this expression to our case

d = (m + ½) λ₀ / 2n

Suppose we measure on the first interference, this is m = 0

d = ½ λ₀ / 2n

let's calculate

d = ½ 496 10⁻⁹ / (2 2.30)

d = 53.9 10-9 m

This is the thickness of the glass, the next wavelength that gives constructive interference is

λ₀ = 2 n d / (m + ½)

let's calculate

λ₀ = 2 2.3 5.39 10-8 / (1 + ½)

λ₀= 4.9588 10-7 m

λ₀= 495.88 nm