Becquerel Becquerel The becquerel (; symbol: Bq) is the SI derived unit of radioactivity. One becquerel is defined as the activity of a quantity of radioactive material in which one nucleus decays per second. The becquerel is therefore equivalent to an inverse second, s. The becquerel is named after Henri Becquerel, who shared a Nobel Prize in Physics with Pierre and Marie Curie in 1903 for their work in discovering radioactivity. As with every International System of Units (SI) unit named for a person, the first letter of its symbol is uppercase (Bq). However, when an SI unit is spelled out
Angular unit the angle is measured as long as each angle is measured in the same unit. One "radian" is the angle subtended by an arc of a circle that has the same length as the circle's radius. The radian is the derived quantity of angular measurement in the SI system. By definition, it is dimensionless, though it may be specified as "rad" to avoid ambiguity. Angles measured in degrees, are shown with the symbol °. Subdivisions of the degree are minute (symbol ', 1' = 1/60°) and second {symbol ", 1" = 1/3600°}. An angle of 360° corresponds to the angle