238 Practical MATLAB® Applications for Engineers
Part b
V I
Y
T
T
15 20
89 10 26 6
3 168 6 6
∠
∠
∠
*.
.
I V
R R
168 6 6
12 5 0
13 4 6 6
∠
∠
∠
.
.
..
I V
C XC
168 6 6
25 90
672 834
∠
∠
∠
.
..
R.3.39 Let us analyze now the RC series case. Evaluate the voltage v(t) of the series RC
circuit, shown in Figure 3.8, assuming that the current is given by
i(t) = Im cos(t)
then
v(t) = Im|Z|c o s (t + )
where Z = R –
j
___
C
ZR
CCRCR
^2
2
(^11111)
and tan tan
Clearly, in a series RC circuit the voltage lags the current by a phase angle
bounded by 0 ≤ θ ≤ (π/2).
R.3.40 Let us analyze the series LC circuit diagram shown in Figure 3.9, and assume that
the current is given by
i(t) = Im cos(t)
then the voltage
v(t) = vL(t) + vC(t) (KVL)
FIGURE 3.7
Network of R.3.38.
IT = 15^20 °
IR IC
R = 12.5Ω X
C = 25Ω
V
FIGURE 3.8
Network of R.3.39.
+ C –
i(t) = Im cos(t)
v(t)
+ R –
+ –