Monday, July 20, 2009

Electric_Circuits_8t h_Edition

Circuit Variables



ElectricaI engineering is an exciting and challcnging profcssion
for anvone who has a genuine interest in, and aptitude lor,
applied science and mathematics. Over the past century and a
hall, electrical engineers have played a dominant rolc in thc
developnrent of svstems that have cbanged the v',ay people live
and work. Satellite commu cation links, telephones, digital com
puters, tcicvisions, diagnostic and surgical medical equipment,
assembiyline robots, and eleclrical power tools are representa-
tive components of systems that define a modern technological
socicty.As an clcctrical engincer. you can participate in this ongo-
ing technological revolution by improvilg and refining these
existing systems and by discovcdng and dcvcloping new systems
to meet the needs ot our ever-changing socjety.




As ]'ou embark on the study of circuit analysis, you nccd to
gain a feel for where tlris study fits into the hierarchy of topics
that conlprise an introduction to electrical engineering. Hence we
begin by presenting an oveNiew of electrical elElineering, some
ideas about an engineering point of view as jt relates to circuit
analysis. and a revierv of the international system of units.
Wc then describe generally what circuit analysis entails. Next,
we intloduce the concepls olvollage and current.We lbllow these
concepts with discussiol of an ideal basic element and the necd
for a polarity reference system. We conclude the chapter by
describing how current and voltage rclatc to powcr and cncrgy.




links
Electric_Circuits_8th_Edition