Page 94 - Schaum's Outline of Theory and Problems of Electric Circuits

AMPLIFIERS AND OPERATIONAL AMPLIFIER CIRCUITS
CHAP. 5]

Fig. 5-31 83

Solved Problems

5.1 In Fig. 5-3, let v ¼ 20 V, R ¼ 10
, R ¼ 990
, k ¼ 5, and R ¼ 3
. Find (a) the The ´ venin
s
i
o
s
equivalent of the circuit seen by R l and (b) v 2 and the power dissipated in R l for R l ¼ 0:5, 1, 3, 5,
10, 100, and 1000
.
(a) The open-circuit voltage and short-circuit current at A–B terminal are v o:c: ¼ 5v 1 and i s:c: ¼ 5v 1 =3,
respectively.
We find v 1 by dividing v s between R s and R i . Thus,
990
R i
v 1 ¼ v s ¼ ð20Þ¼ 19:8V
R s þ R i 10 þ 990

Fig. 5-32