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

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

Answer: (A)

Verified step by step guidance

1. Recall the electromagnetic spectrum, which arranges types of electromagnetic radiation by their wavelength or 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 (approximately \( 3.00 \times 10^{8} \, m/s \)).
3. Identify the relative positions of the given types of radiation on the electromagnetic spectrum: X-rays have very short wavelengths, ultraviolet light has shorter wavelengths than visible light, and radio waves have the longest wavelengths.
4. Compare the options by their typical wavelength ranges: - X-rays: about \( 10^{-12} \) to \( 10^{-9} \) meters - Ultraviolet light: about \( 10^{-8} \) to \( 4 \times 10^{-7} \) meters - Visible light: about \( 4 \times 10^{-7} \) to \( 7 \times 10^{-7} \) meters - Radio waves: from about \( 10^{-1} \) meters up to kilometers
5. Conclude that since radio waves have the longest wavelength among the options, they are the correct answer.