magnetic units
121radioactivity — /ray dee oh ak tiv i tee/, n. Physics, Chem. the phenomenon, exhibited by and being a property of certain elements, of spontaneously emitting radiation resulting from changes in the nuclei of atoms of the element. Also called activity. [1895… …
122dating — I In geology and archaeology, the process of determining an object s or event s place within a chronological scheme. Scientists may use either relative dating, in which items are sequenced on the basis of stratigraphic clues (see stratigraphy) or …
123Nikola Tesla — Tesla, aged 37, 1893, photo by Sar …
124Refrigeration — Commercial refrigeration Ice is used to refriger …
125Constitutive equation — Many defining equations are in the form of a constitutive equation, since parameters of a property or effect associated matter are characteristic to the substance in question. A large number of other defining equations not specifically… …
126Electromagnetic clutch — Electromagnetic clutches operate electrically, but transmit torque mechanically. This is why they used to be referred to as electro mechanical clutches. Over the years, EM became known as electromagnetic versus electro mechanical, referring more… …
127Magnetostratigraphy — is a geophysical correlation technique used to date sedimentary and volcanic sequences. The method works by collecting oriented samples at measured intervals throughout the section. The samples are analyzed to determine their characteristic… …
128photography, technology of — Introduction equipment, techniques, and processes used in the production of photographs. The most widely used photographic process is the black and white negative–positive system (Figure 1 >). In the camera the lens projects an image of… …
