Page 46 - Schaum's Outline of Theory and Problems of Electric Circuits

CIRCUIT LAWS
CHAP. 3]

Fig. 3-23 35
3.22 In the circuit Fig. 3-23, v s1 ¼ 0, v s2 ¼ 6V, i s1 ¼ 6A, i s2 ¼ 12 A. For the four cases of (a) R ¼ 0,
(b) R ¼ 6
, (c) R ¼ 9
, and (d) R ¼ 10 000
, draw the simplified circuit and find i BA and v AC .
8
> ðaÞ i BA ¼ 5:33; v AC ¼ 34
>
>
<
Ans: ðbÞ i BA ¼ 3:2; v AC ¼ 27:6 (All in A and V)
> ðcÞ i BA ¼ 2:66; v AC ¼ 26
>
>
:
ðdÞ i BA ¼ 0:005 0; v AC ¼ 18:01 18
3.23 In the circuit of Fig. 3-24, (a) find the resistance seen by the voltage source, R in ¼ v=i, as a function of a,
and (b) evaluate R in for a ¼ 0; 1; 2. Ans. (a) R in ¼ R=ð1 aÞ; (b) R; 1; R

Fig. 3-24

3.24 In the circuit of Fig. 3-24, (a) find power P delivered by the voltage source as a function of a, and
2
2
2
(b) evaluate P for a ¼ 0; 1; 2. Ans. (a) P ¼ v ð1 aÞ=R;(b) v =R; 0; v =R
3.25 In the circuit of Fig. 3-24, let a ¼ 2. Connect a resistor R x in parallel with the voltage source and adjust it
within the range 0 R x 0:99R such that the voltage source delivers minimum power. Find (a) the value
of R x and (b) the power delivered by the voltage source.
2
Ans. (a) R x ¼ 0:99R, (b) P ¼ v =ð99RÞ

Fig. 3-25