Here's why:
* Snell's Law: This law governs the relationship between the angles of incidence and refraction: n₁sinθ₁ = n₂sinθ₂
* n₁ and n₂ are the refractive indices of the two materials.
* θ₁ is the angle of incidence.
* θ₂ is the angle of refraction.
* Perpendicular Incidence: When the light ray is perpendicular to the boundary, the angle of incidence (θ₁) is 0°.
* Applying Snell's Law:
* n₁sin(0°) = n₂sinθ₂
* sin(0°) = 0
* 0 = n₂sinθ₂
* Solving for the Angle of Refraction: For the equation to hold true, sinθ₂ must also be 0. The only angle where sinθ = 0 is when θ = 0°.
Therefore, the angle of refraction is zero degrees, meaning the light ray continues straight through the boundary without changing direction.
