What range of the spectrum is primarily used for communication?

• A. Infrared
• B. Ultraviolet
• C. Visible Light
• D. Radiofrequency Radiation

Answer: (D)

Communications rely on a part of the spectrum that can cover long distances, pass through the atmosphere, and be handled by practical hardware. Radiofrequency radiation fits that role because radio waves propagate well in air, can diffract around objects, and allow antennas of manageable size for mobile and fixed systems. The RF spectrum is also heavily allocated and standardized, enabling global wireless networks (cellular, Wi‑Fi, broadcasting, satellite). Infrared would require close, line-of-sight and is easily blocked or absorbed; ultraviolet is largely absorbed by the atmosphere and can be hazardous; visible light can support very high data rates but typically needs line-of-sight or fiber and is less versatile for long-range wireless. Therefore, the spectrum most commonly used for communication is radiofrequency radiation.