Question

initially the angle 0 is much less than the critical angle for this light in water the laser moves and 0 gradually increases untill it is much greater than the critical angle describe for different angle of the laser what happens to the light beam after it hits the surface​

Answer 1

low angle n₁ sin θ₁ = n₂ sin θ₂

critical angle sin θ₁ =
`(n2)/(n1)` θ₁ = θ_{reflected}

Step-by-step explanation:

When the light ray touches the two surfaces of the refraction according to the Law of Refraction

n₁ sin θ₁ = n₂ sin θ₂

In this problem the ray goes from the material with the highest index to the lowest index, in the middle of the incident it has the subscript 1

sin θ₂ =
`(n_1)/(n_2)` sin θ₂

What

n₁/n₂> 1

in refracted ray it moves away from normal.

As the incident angle increases, a value is reached where sin θ₂ = 1, for this angle

sin θ₁ =
`(n2)/(n1)`

This angle is called critical and as the sine function cannot have values greater than 1, the ray is reflected, therefore it must comply with the law of reflection where the incident angle is equal to the reflected angle.