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Human body temperature varies. It depends on sex, age, time of day, exertion level, health status (such as illness and menstruation), what part of the body the measurement is taken at, state of consciousness (waking, sleeping, sedated), and emotions. Body temperature is kept in the normal range by a homeostatic function known as ...
A black body is also a perfect emitter. The radiation of such perfect emitters is called black-body radiation. The ratio of any body's emission relative to that of a black body is the body's emissivity, so a black body has an emissivity of one. Absorptivity, reflectivity, and emissivity of all bodies are dependent on the wavelength of the ...
A black-body with a temperature at or below room temperature would thus appear absolutely black, as it would not reflect any incident light nor would it emit enough radiation at visible wavelengths for our eyes to detect. Theoretically, a black-body emits electromagnetic radiation over the entire spectrum from very low frequency radio waves to ...
Two of the essential elements that make up the human body, namely potassium and carbon, have radioactive isotopes that add significantly to our background radiation dose. An average human contains about 17 milligrams of potassium-40 (40 K) and about 24 nanograms (10 −9 g) of carbon-14 (14 C), [17] (half-life 5,730 years). Excluding internal ...
Dose equivalent calculates the effect of radiation on human tissue. [4] This is done using tissue weighting factor, which takes into account how each tissue in the body has different sensitivity to radiation. [4] The effective dose is the risk of radiation averaged over the entire body. [4] Ionizing radiation is known to cause cancer in humans. [4]
There is a small increase in the dose, due to naturally occurring gamma radiation, around small particles of high atomic number materials in the human body caused by the photoelectric effect. [24] By comparison, the radiation dose from chest radiography (about 0.06 mSv) is a fraction of the annual naturally occurring background radiation dose. [25]
The walls, ceiling, and floor are all at the same temperature. For an average person, the outer surface area is 1.4 m 2, the surface temperature is 30 °C, and the emissivity (ε) is 0.95. Emissivity is the ability of a surface to emit radiative energy compared to that of a black body at the same temperature. [2]
When radioactive compounds enter the human body, the effects are different from those resulting from exposure to an external radiation source. Especially in the case of alpha radiation, which normally does not penetrate the skin, the exposure can be much more damaging after ingestion or inhalation.