Which ranking correctly orders electromagnetic radiation from low energy to high energy?

• A. Microwaves, infrared, visible, UV, x-rays, gamma, cosmic
• B. Cosmic, gamma, x-rays, UV, visible, infrared, microwaves
• C. UV, visible, infrared, microwaves, x-rays, cosmic, gamma
• D. UV, visible, infrared, cosmic, gamma, microwaves, x-rays

Answer: (B)

Energy increases with frequency, and since frequency is inversely related to wavelength, photons with longer wavelengths carry less energy than those with shorter wavelengths. So, to rank electromagnetic radiation from lowest to highest energy, you start with the longest wavelengths: microwaves, then infrared, then visible light, followed by ultraviolet, X-rays, and finally gamma rays as the highest-energy photons.

The term “cosmic” isn’t a standard category of electromagnetic radiation and can be ambiguous, which makes it problematic in a strict energy ranking. If we stick to the well-established EM bands, the progression from lowest to highest energy is microwaves → infrared → visible → ultraviolet → X-rays → gamma rays.