A ray diagram shows the ray passing from medium 1 to medium 2. After passing into medium 2, the ray bends away from the normal. What does this ray diagram illustrate?

When light enters a less optically dense medium, it bends away from the normal. Since the ray bends away from the normal as it passes from medium 1 into medium 2, medium 1 is denser than medium 2. This illustrates refraction with medium 1 denser than medium 2.

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