Unformatted text preview: Kirchhoff's laws.To aid the analysis, we introduce the curent i as shown in Fig. 3.12(b). From Kilchhoff's current la\ Rr and R, carry the same cur-rel1l.Applyilg Kilchhoff's voltage law around the closed loop yields r . - l R r + i R z , R r + R , Now wc can use Ohm's law to calculale ul and ,2: Equations 3.21 and 3.22 show that ,r and o, are fractions of o,- Each ftaction is the ratio of the resistance across which rhe divided voltage is defined to the sum ofthe two resistances. Because this ratio is always lcss than 1.0. the divided voltages or and ?J2 are always iess than the source If you desire a particular valuc of ?)2, and o, is specified, an infinile number ofcombinarions of Rr and R, yicld thc propcr ratio. For example, suppose that !. equals 15 V and 1J2 is to bc 5 V Thon r2/o, = i and, liom...
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- Spring '07
- Trigraph, nd, Simph sistive ircuits