Which description best matches ionizing radiation?

Which description best matches ionizing radiation?

• A. Ionizing radiation
• B. Ultraviolet and beyond
• C. Visible light
• D. High energy visible light

Answer: (D)

Ionizing radiation is radiation energetic enough to knock electrons off atoms. A photon's energy must exceed an electron’s binding energy to ionize the atom. Ultraviolet photons, and higher-energy radiation such as X-rays and gamma rays, have enough energy to do this, so they’re classed as ionizing. Visible light, even at the higher end of the spectrum, usually doesn’t have enough energy per photon to overcome most atoms’ ionization energies, so it’s not ionizing. That’s why describing ionizing radiation as ultraviolet and beyond is the best match.

Ionizing radiation is radiation energetic enough to knock electrons off atoms. A photon's energy must exceed an electron’s binding energy to ionize the atom. Ultraviolet photons, and higher-energy radiation such as X-rays and gamma rays, have enough energy to do this, so they’re classed as ionizing. Visible light, even at the higher end of the spectrum, usually doesn’t have enough energy per photon to overcome most atoms’ ionization energies, so it’s not ionizing. That’s why describing ionizing radiation as ultraviolet and beyond is the best match.