Refraction and Lenses - Mission RL2 Detailed Help

In the diagram at the right, a light ray is shown passing from medium 1 to medium 2. The angle of refraction for this ray is represented by angle ____.

Definition of Angle of Refraction:
The angle of refraction is the angle made between the ray of light entering the new medium (refracted ray) and the normal line drawn to the surface at the location where the ray enters into the new medium.

A common mistake made by beginning physics students is to believe that the angle of refraction is the angle between the refracted ray and the boundary. But don't be fooled! Angles of refraction (and incidence) are always measured between the ray of light and the normal line.

The diagram shows two media (shaded pink and yellow), a solid black boundary line, a normal line (dashed) and an incident and refracted ray (red). The letters are used as labels to represent the various angles between the normal line, light ray, boundary, etc.