strålnings

Strålnings, or radiation, refers to energy emitted by a source and propagating through space or matter. It can take the form of electromagnetic waves (such as visible light, X-rays, or radio waves) or moving particles (such as electrons, protons, or neutrons). A central division is between ionizing radiation, which has enough energy to remove electrons from atoms, and non-ionizing radiation, which does not.

Ionizing radiation includes X-rays, gamma rays, alpha and beta particles, and cosmic rays. It can cause chemical changes in materials and biological tissue, potentially leading to mutations or cancer with sufficient exposure. Non-ionizing radiation includes visible light, infrared, microwaves, radio waves, and ultraviolet bands below the ionization threshold; ultraviolet can be ionizing at very short wavelengths, though typical solar ultraviolet has limited penetration.

Measurement and safety: The absorbed dose is measured in gray (Gy). The biological effect is expressed as the equivalent or effective dose in sievert (Sv). Activity of radioactive sources is measured in becquerels. Exposure is influenced by distance, shielding, and duration. Protection principles include shielding, limiting time, and increasing distance; the ALARA principle aims to minimize exposure.

Sources: Natural background radiation comes from cosmic rays and Earth's crust; human-made sources include medical imaging (X-ray, CT), radiotherapy, nuclear power, industrial radiography. Applications: Medical diagnosis and treatment, industrial testing, research, and energy generation.

History: The discovery of X-rays by Wilhelm Röntgen in 1895 and later work on radioactivity and nuclear medicine helped shape modern science and medicine.