Important Definitions
Impedance is a complex number and is defined as the ratio of the phasor
voltage to the phasor current. The Unit of measurement is the Ohm. Z=V/I, where
V and I are complex numbers, and represent the volatge and current respectively.
Admittance is a complex number and is defined as the reciprocal of impedance.
The Unit of measurement is the Siemens. Y=1/Z, where Z is a complex number and
represents the impedance.
Reactance is a real number and is defined as the imaginary part of the
impedance. The Unit of measurement is the Ohm. X=Im(Z), where Z is a complex
number and represents the impedance.
Susceptance is a real number and is defined as the imaginary part of the
admittance. The Unit of measurement is the Siemens. B=Im(Y), where Y is a
complex number and represents the admittance.
Apparent Power is a real number and is defined as the product of the rms
voltage and the rms current. The Unit of measurement is the VoltAmpere.
Active Power is a real number and is defined as the product of the rms
voltage, the rms current and the cosine of the angle between them. The Unit of
measurement is the Watt.
Quadrature Power is a real number and is defined as the Imaginary part of the
Complex Power. The Unit of measurement is the VoltAmpere Reactive (var). Q=Im(S),
where S represents the complex power.
Power Factor is the cosine of the angle between the voltage and current
phasors. it is leading if the angle is positive and lagging if the angle is
negative.
A Bode plot is a sketch of magnitude, expressed in decibels(dB), and phase
versus the logarithm of frequency. These are useful in the frequency analysis of
filters and network functions.
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