Sievert Sievert The sievert (symbol: Sv) is a derived unit of ionizing radiation dose in the International System of Units (SI) and is a measure of the health effect of low levels of ionizing radiation on the human body. The sievert is of importance in dosimetry and radiation protection, and is named after Rolf Maximilian Sievert, a Swedish medical physicist renowned for work on radiation dose measurement and research into the biological effects of radiation. The sievert is used for radiation dose quantities such as equivalent dose and effective dose, which represent the risk of external radiation from sources outside the
Non-ionizing radiation Planck's law of radiation. Wien's displacement law gives the most likely frequency of the emitted radiation, and the Stefan–Boltzmann law gives the heat intensity (power emitted per area). Parts of the electromagnetic spectrum of thermal radiation may be ionizing, if the object emitting the radiation is hot enough (has a high enough temperature). A common example of such radiation is sunlight, which is thermal radiation from the Sun's photosphere and which contains enough ultraviolet light to cause ionization in many molecules and atoms. An extreme example is the flash from the detonation of a nuclear weapon, which emits a large