Which statement best describes radio waves?

• A. They have the longest wavelengths.
• B. They are shorter than infrared waves.
• C. They cannot be used for communication.
• D. They are higher energy than ultraviolet.

Answer: (A)

Radio waves sit at the low-frequency end of the electromagnetic spectrum, so they have the longest wavelengths. Because wavelength and frequency are inversely related, longer wavelengths mean lower frequencies. This property lets radio waves propagate well through the atmosphere and around obstacles, which is why they’re used for broadcasting and communication. The claim that they are shorter than infrared waves is incorrect—infrared waves have shorter wavelengths than radio waves. They can be used for communication, so saying they cannot would be false. And radio waves have lower energy per photon than ultraviolet photons, so they are not higher energy than ultraviolet. The statement about having the longest wavelengths best describes radio waves.