What two factors influence the path of a light ray as it passes through a transparent medium?

• A. Angle of incidence, the index of refraction
• B. Wavelength and amplitude
• C. Speed of light and medium density
• D. Color and transparency

Answer: (A)

When a light ray crosses a boundary between two transparent media, it bends because light travels at different speeds in each medium. The direction of that bend is governed by Snell’s law, which links the angle at which the light hits the boundary (the angle of incidence) with how much the light is slowed by the medium (the refractive index). The combination of these two factors—the incidence angle and the index of refraction of the media—determines the refracted path.

If the light hits straight on (normal incidence), it doesn’t bend, even though its speed changes. Wavelength does change inside the medium, and amplitude can be affected by reflection, but those do not determine the path the ray takes through the boundary. Color and transparency describe appearance, not the bending direction.