Which statement about non-ionizing radiation is true?

• A. It is always dangerous
• B. It has enough energy to ionize most atoms
• C. It can cause immediate severe burns
• D. It generally does not have enough energy to eject electrons

Answer: (D)

Non-ionizing radiation carries photon energies that are typically too small to knock electrons off atoms. Ionization requires a certain energy threshold, and for most atoms that threshold is higher than the energy carried by visible light, infrared, microwaves, and radio waves. Because of this, these radiations generally interact with matter through heating or excitation rather than by ejecting electrons, which is why the statement about not having enough energy to eject electrons is correct. It’s worth noting that at extreme wavelengths or very high energies (certain ultraviolet photons, for example) ionization can occur, but for the broad class of non-ionizing radiation, ionization does not happen under ordinary exposure. Non-ionizing radiation can still cause heating or other non-ionizing effects, but immediate severe burns are not a general characteristic of it.