 
TM 9254
73.
Alternating Current  Continued
(a)
For parallel circuits:
RX
Z =
R^{2} + X^{2}
(b)
For series circuits:
Z =
R^{2} + X^{2}
Where:
Z is the total impedance in ohms.
R is the total resistance in ohms.
X is the total reactance in ohms.
e.
Instantaneous Values of AC Voltage. As the AC voltage and current pass through the sine wave cycle
depicted in figure 78, there are several instantaneous values of interest, such as the peak, effective, and average values
of the sine wave.
Figure 78. Instantaneous Values of AC
The relationships between the instantaneous values shown are provided in table 73. Given any one of the four values,
the remaining three values can be calculated using the relationships from the table.
Table 73. Instantaneous Values of AC
Given
Multiplying factor to get
Values
Average
Effective
Peak
PeaktoPeak
Average

1.11
1.57
3.14
Effective
0.9

1.414
2.828
Peak
0.637
0.707

2.0
PeaktoPeak
0.32
0.3535
0.5

78
