radiations

Radiations, in the plural form, refer to the various forms of energy and particles that propagate through space or matter. They include electromagnetic radiation and particle radiation, and they can be either ionizing or non-ionizing, depending on the energy carried by the quanta or particles.

Electromagnetic radiation consists of oscillating electric and magnetic fields. Its energy increases with frequency and spans a spectrum from radio waves to gamma rays. Ionizing electromagnetic radiation includes X-rays, gamma rays, and high-energy ultraviolet light, while visible light, infrared, microwaves, and low-energy ultraviolet light are typically non-ionizing.

Particle radiation involves subatomic particles emitted by nuclei or produced in accelerators. Alpha particles are helium nuclei with low penetration; beta particles are electrons or positrons with greater range; neutrons have no charge and interact through nuclear forces. Some particle radiations are strongly ionizing.

Sources include natural origins such as cosmic rays, radon gas, and uranium- and thorium-bearing minerals, and artificial origins such as medical imaging, radiotherapy, industrial radiography, nuclear power, and research accelerators.

Measurement and safety: radiation exposure is quantified with units such as the becquerel (activity), gray (absorbed dose), and sievert (biological effect). Protection relies on shielding, monitoring, and minimizing exposure time and distance. Biological effects range from tissue damage at high doses to increased cancer risk at lower doses, with cumulative risk a concern over time.