Which statement correctly describes visible light?

• A. It comprises electromagnetic waves visible to the human eye
• B. It comprises waves not visible to the human eye
• C. It is only produced by LEDs
• D. It has frequencies below those of microwaves

Answer: (A)

Visible light is the portion of the electromagnetic spectrum that human eyes can detect. It consists of electromagnetic waves with wavelengths roughly 380–750 nanometers, which correspond to frequencies about 4×10^14 to 7.5×10^14 hertz. All electromagnetic waves travel at the same speed in a vacuum—the speed of light—so visible light is just one range within that spectrum, not tied to a single source. It is produced by many sources, not just LEDs, including the Sun, lamps, and flames. The idea that visible light has frequencies below microwaves is incorrect because microwaves have lower frequencies than visible light. Therefore, visible light comprises electromagnetic waves visible to the human eye.