Which statement about infrared rays, microwaves, and radio waves is true?

Which statement about infrared rays, microwaves, and radio waves is true?

• A. These types of radiation surround us constantly, and are not harmful, because their frequencies are so low.
• B. They have the highest energies among radiations.
• C. They cannot travel through space.
• D. They are all deadly to living organisms.

Answer: (A)

Infrared, microwaves, and radio waves are examples of non‑ionizing radiation. Their photons have relatively low energy because the energy of a photon is proportional to its frequency (E = hf). That low energy isn’t enough to knock electrons off atoms or break chemical bonds, so these waves don’t ionize matter. Because of this, and because these waves are common in daily life (from warmth and remote controls to wireless signals and radio broadcasts), they surround us constantly and are generally not harmful under normal exposure. It’s true that very intense microwaves can heat tissue, but at typical levels they don’t cause harm. In contrast, higher‑energy radiation like X‑rays and gamma rays can ionize, which is why those options aren’t true for these waves.

Infrared, microwaves, and radio waves are examples of non‑ionizing radiation. Their photons have relatively low energy because the energy of a photon is proportional to its frequency (E = hf). That low energy isn’t enough to knock electrons off atoms or break chemical bonds, so these waves don’t ionize matter. Because of this, and because these waves are common in daily life (from warmth and remote controls to wireless signals and radio broadcasts), they surround us constantly and are generally not harmful under normal exposure. It’s true that very intense microwaves can heat tissue, but at typical levels they don’t cause harm. In contrast, higher‑energy radiation like X‑rays and gamma rays can ionize, which is why those options aren’t true for these waves.