PRACTICAL MATLAB® FOR ENGINEERS PRACTICAL MATLAB

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 –

+ –