When a ray of light passes from air into glass, the angle it makes with the surface normal will decrease. This is due to the phenomenon called refraction.

Here's why:

* Refractive Index: Glass has a higher refractive index than air. This means light travels slower in glass than in air.

* Snell's Law: This law describes the relationship between the angles of incidence and refraction, and the refractive indices of the two mediums:

* n₁sinθ₁ = n₂sinθ₂

* where n₁ and n₂ are the refractive indices of the first and second mediums, and θ₁ and θ₂ are the angles of incidence and refraction, respectively.

Since n₂ (glass) is greater than n₁ (air), for the equation to hold true, θ₂ (the angle of refraction) must be smaller than θ₁ (the angle of incidence).

In simpler terms: The light ray bends towards the normal as it enters the denser medium (glass).