PRACTICAL MATLAB® FOR ENGINEERS PRACTICAL MATLAB

272 Practical MATLAB® Applications for Engineers

The script fi le vol_RL is executed and the results are as follows:

>> vol _ RL

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The peak value (in volts) and the phase (in degrees) of v(t) are=

Vmax =

250

Phasedegree =

36.8699

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The preceding result means that v(t) = 250 cos(100t + 36.8699°) V.

Example 3.5

Evaluate the current i(t) for the circuit shown in Figure 3.53 by hand, and by using

MATLAB.

ANALYTICAL Solution

V = 200 ∠0°, Z = 20 –

j

_____________

125 ∗ 10 –^6 ∗ 500

= 20 – j 16

then

I V

Zj j





(^200)

20 16
50
54
7 8 38 6..∠ A
Therefore, i(t) = 7.8 cos(500t + 38.6°) A.
MATLAB Solution

W = 500;
V = 200;
R = 20;
C = 125e-6
FIGURE 3.53
Network of Example 3.5.
C = 125 μ F
i(t)
v(t) = 200 cos(500 t) V R = 20 Ω