What type of radiation is non-ionizing?

Non-ionizing radiation refers to electromagnetic radiation that does not have enough energy to remove tightly bound electrons from atoms or molecules. This means it does not have enough energy to ionize atoms, which is why it is generally considered to be less harmful than ionizing radiation, which can be damaging to biological tissues and alter cellular structures.

Ultraviolet (UV) radiation is classified as non-ionizing radiation. While UV radiation can still cause biological effects, such as skin damage and increased risk of skin cancer with excessive exposure, it does not possess the capability to ionize atoms. Instead, its energy is primarily manifested in its ability to cause chemical reactions—like producing vitamin D in the skin or leading to tanning.

The other forms of radiation mentioned are classified as ionizing radiation. For example, X-rays and gamma rays have enough energy to ionize atoms, which is why they are used in medical imaging and treatments but require careful control and protection to avoid damage to living tissues. Radioactivity, in the context of the question, refers to the emissions from radioactive materials, which also typically includes ionizing radiation. Thus, UV radiation stands out as the correct answer in this context of non-ionizing radiation.