Which of the following categories of electromagnetic radiation has the longest wavelength?

• A. X-rays
• B. Ultraviolet
• C. Radio waves
• D. Visible light

Answer: (C)

Verified step by step guidance

1. Recall that electromagnetic radiation is categorized by wavelength, with longer wavelengths corresponding to lower energy and frequency.
2. List the given categories in order of increasing wavelength: X-rays, Ultraviolet, Visible light, and Radio waves.
3. Understand that X-rays have very short wavelengths, followed by Ultraviolet which has slightly longer wavelengths, then Visible light with even longer wavelengths.
4. Recognize that Radio waves have the longest wavelengths among the options provided, often ranging from millimeters to kilometers.
5. Conclude that Radio waves have the longest wavelength compared to X-rays, Ultraviolet, and Visible light.