GED Science TestPhysical ScienceMedium
A student is observing a beam of white light as it passes through a triangular prism. They notice that the white light separates into its constituent colors (a spectrum). What phenomenon is responsible for this separation?
- ARefraction
- BReflection
- CDispersion
- DDiffraction
Show answer & explanationAnswer & explanation
Correct answer: C. Dispersion
Dispersion is the phenomenon where white light separates into its component colors (a spectrum) when passing through a medium, such as a prism, because different wavelengths of light travel at slightly different speeds in that medium and therefore refract at different angles.
Why the other options are wrong
- A. Refraction is the bending of light as it passes from one medium to another, but dispersion is the specific type of refraction that separates colors.
- B. Reflection is the bouncing back of light from a surface.
- D. Diffraction is the bending of light waves as they pass around obstacles or through narrow openings.
Dispersion of Light
The phenomenon where white light separates into its constituent colors when it passes through a medium like a prism, due to different wavelengths having different refractive indices.
- Creates a spectrum (e.g., rainbow).
- Caused by the dependence of a medium's refractive index on wavelength.
- Red light refracts less than violet light in most transparent media.
Memory trick: Light interacts in many ways: bouncing, bending, splitting, spreading.