Dictionary of Energy



A chemical element (atomic number Z = 89, symbol Ac) which is one of the group of elements known collectively as the actinides. Actinium occurs naturally in minute amounts, mainly the isotope 227Ac, as part of the decay chain of…


The collective name given to a series of chemically similarmetallic elements which includes those which are valuable for nuclear fissionenergy production and those sustaining, by radioactivity, the earth's internalheat.


A gas (C₂H₂) which was often used as a fuel for lighting before electricity became widely available. It remains important in oxyacetylene burners for cutting and welding metals at temperatures which can exceed 3,000 C.


(1) a storage cell which accumulates electrical energy in chemical form, i.e. a battery. The term 'accumulator' is used especially of lead-acid batteries such as those used in automobiles. (2) A reservoir of cooling water used in certain emergency core-…


(Sometimes called absorptance, or absorptive power) When radiation falls onto a surface, some is reflected and some absorbed; the proportion absorbed is the absorptivity of the surface. It may vary according to the wavelength of the radiation, and so may…

Absolute zero

The lowest temperature to which any substance could conceivably be cooled,and at which it would contain no remaining energy in the from of heat. Absolute zero is close to - 273 C and is by definition the zero of the…