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

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

Answer: (D)

Verified step by step guidance

1. Recall the electromagnetic spectrum, which orders types of electromagnetic radiation by their wavelength and frequency.
2. Understand that wavelength (\( \lambda \)) and frequency (\( \nu \)) are inversely related by the equation: \[ \lambda = \frac{c}{\nu} \] where \( c \) is the speed of light.
3. Identify the relative positions of the given types of radiation on the electromagnetic spectrum: X-rays have very short wavelengths, ultraviolet light has slightly longer wavelengths than X-rays, visible light has longer wavelengths than ultraviolet, and radio waves have the longest wavelengths.
4. Compare the options given (X-rays, ultraviolet light, visible light) with radio waves, noting that radio waves have wavelengths much longer than all the others listed.
5. Conclude that among the options, radio waves have the longest wavelength because they lie at the low-frequency, long-wavelength end of the electromagnetic spectrum.