What is visible light?

• A. The portion of the electromagnetic spectrum visible to the human eye; colors from red to violet.
• B. Energy that is produced by electricity.
• C. The energy stored in chemical bonds.
• D. The force that holds protons in the nucleus.

Answer: (A)

Visible light is the portion of the electromagnetic spectrum that the human eye can detect. It includes wavelengths roughly from 380 to 750 nanometers and spans the colors red through violet. When these wavelengths reach the eye, cone cells in the retina respond to different ranges of light, and the brain combines that information to produce our perception of color. The other options describe different kinds of energy or forces—electric energy, chemical energy, and the nuclear force—so they aren’t what we mean by visible light.