Chapter 21 : Alternating current circuits and electromagnetic waves

Example 21.1 Page No: 698

In [1]:
from __future__ import division
from math import sqrt
V_max=200#in V
V_rms=(V_max)/sqrt(2)
R=100#in ohm
I_rms=V_rms/R
print "Voltage = %0.2f V"%V_rms
print "Current = %0.2f Amps"%I_rms

Voltage = 141.42 V
Current = 1.41 Amps

Example 21.2 Page No: 700

In [4]:
C=8*10**-6
X_c=1/(377*C)
print "Resistance = %0.2f ohm"%X_c
I_rms=150/X_c
print "Current = %0.2f Amps"%I_rms

Resistance = 331.56 ohm
Current = 0.45 Amps

Example 21.3 Page No: 702

In [5]:
L=25*10**-3#In H
w=377
X_L=w*L#In ohm
print "Resistance = %0.2f ohm"%X_L
I_rms=150/X_L#In A
print "Current = %0.2f Amps"%I_rms

Resistance = 9.43 ohm
Current = 15.92 Amps

Example 21.4 Page No: 706

In [6]:
from math import atan, degrees, sqrt
R=250#in ohm
Xc=758#in ohm
Xl=226#in Ohm
X=Xl-Xc
V_max=150#in Volt
Z=sqrt(R**2+X**2)
I=V_max/Z
q=degrees(atan(X/R))
print "Impedence = %0.2f ohm"%Z
print "Current = %0.2f Amps"%I
print "Angle = %0.2f degree"%q
V_R=I*R
V_C=I*Xc
V_L=I*Xl
print "Voltage at Resistance = %0.2f Volt"%V_R
print "Voltage at Inductance = %0.2f Volt"%V_L
print "Voltage at Capacitance = %0.2f Volt"%V_C

Impedence = 587.81 ohm
Current = 0.26 Amps
Angle = -64.83 degree
Voltage at Resistance = 63.80 Volt
Voltage at Inductance = 57.67 Volt
Voltage at Capacitance = 193.43 Volt

Example 21.5 Page No: 708

In [7]:
from math import sqrt
V_max=150#in V
V_rms=(V_max)/sqrt(2)
I_max=.255#in ohm
I_rms=I_max/sqrt(2)
cos=.426
P=V_rms*I_rms*cos
print "Voltage = %0.2f V"%V_rms
print "Current = %0.2f Amps"%I_rms
print "Power = %0.2f watt"%P

Voltage = 106.07 V
Current = 0.18 Amps
Power = 8.15 watt

Example 21.6 Page No: 709

In [9]:
L=20*10**-3#in H
C=1/(25*10**6*L)
print "Capacitance = %0.e Farad"%C

Capacitance = 2e-06 Farad

Example 21.7 Page No: 711

In [10]:
I1=100
v1=4*10**3
v2=2.40*10**5
I2=(I1*v1)/v2
R=30#in ohm
p_lost=I2*I2*R
P_output=I1*v1
p_per=(p_lost*100/P_output)
print "Solution a"
print "Percentage of power lost = %0.2f"%p_per
P_lost=I1*I1*R
per=(P_lost*100)/(4*10**5)
print "Solution B"
print "Percentage of power lost = %0.2f"%per

Solution a
Percentage of power lost = 0.02
Solution B
Percentage of power lost = 75.00