What is a characteristic of non-ionizing radiation?

Non-ionizing radiation is defined by its inability to ionize atoms; that is, it does not carry enough energy to remove tightly bound electrons from their orbits around the nucleus. This characteristic is crucial because it differentiates non-ionizing radiation from ionizing radiation, which includes X-rays and gamma rays that do have sufficient energy to ionize atoms and, consequently, can cause chemical changes and biological damage.

Understanding this distinction is fundamental in the field of radiation safety, as non-ionizing radiation typically poses a lower risk of biological harm compared to its ionizing counterpart. Examples of non-ionizing radiation include visible light, radio waves, and microwaves, all of which interact with atoms without causing ionization.

In terms of the other options, the statement that non-ionizing radiation can cause excitations in atoms is misleading; while non-ionizing radiation cannot remove electrons, it can elevate electrons to higher energy states, leading to vibrations or rotations in molecules. Additionally, non-ionizing radiation cannot penetrate all types of materials; for instance, certain non-ionizing radiation like ultraviolet light can be absorbed by the outer layers of the skin or other materials.