Answer:
when the ray passes from ice to perspex it must approach the normal
Explanation:
This is an exercise in refraction of light, the process is governed by the expression
n₁ sin θ₁ = n₂ sin θ₂
where we use index 1 for the incident medium and subscript 2 for the scattered medium.
In our case, medium 1 is ice with the lowest refractive index.
sin θ₁ = n₂ / n₁ sin θ₂
To fulfill this equation, if the ray travels through the medium 1 ice with an angle θ₁, the angle in the medium 2 perspex must be smaller so that the sine is smaller, so when the ray passes from ice to perspex it must approach the normal
