Which statement best describes radio waves?

• A. Visible light
• B. Electromagnetic waves with the longest wavelengths and lowest frequencies
• C. Mechanical waves that require a medium to travel
• D. Waves that travel fastest in vacuum

Answer: (B)

Radio waves are a type of electromagnetic wave, so they can travel through space without needing a medium. What specifically defines them is that they have the longest wavelengths and the lowest frequencies within the electromagnetic spectrum. That means their waves are far longer than visible light, and their signals operate at lower frequencies, which is why they’re suited for long-distance communication and reception with antennas. In vacuum, all electromagnetic waves travel at the same speed, so describing radio waves as “fastest in vacuum” doesn’t distinguish them from other EM waves. The other statements describe either visible light, mechanical waves, or a property shared by all electromagnetic waves, not what makes radio waves unique.