What phenomenon describes the bending of light as it passes between media?

• A. Refraction
• B. Reflection
• C. Absorption
• D. Diffraction

Answer: (A)

Light bending as it passes from one medium to another happens because the light changes speed when it enters a material with a different optical density. That change in speed causes the path to tilt, which is refraction. The degree of bending depends on how different the media are, and it’s described by Snell’s law: n1 sin(angle in) = n2 sin(angle out). A common example is a straw looking tilted in a glass of water. Refraction is distinct from reflection (bouncing off a surface), absorption (light energy taken up by the material), and diffraction (bending around edges or through narrow openings).