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Q or Figure of Merit  Impedance (cont.)  
of a simple reactor 
In series circuits where phase
angle and any two of the Z, R and X components are known, the unknown component may be determined from the expressions: 

of a single capacitor 


where  Q = 
a ratio expressing the figure of
merit, 
where  Z =  magnitude of impedance in ohms,  
X_{L} =  inductive reactance in ohms,  R =  resistance in ohms,  
X_{C} =  capacitive reactance in ohms,  X = 
reactance (inductive or
capacitive) in ohms, 

R_{L} = 
resistance in ohms acting in series
with inductance, 
Nomenclature  
R_{C} = 
resistance in ohms acting in series
with capacitance, 
Z = 
absolute or numerical value of
impedance magnitude in ohms, 

Impedance  R =  resistance in ohms,  
In any ac circuit where
resistance and reactance values of the R, L and C components are given, the absolute or numerical magnitude of impedance and phase angle can be computed from the formulas which follow: 
X_{L} =  inductive reactance in ohms,  
X_{C} =  capacitive reactance in ohms,  
L =  inductance in henrys,  
C =  capacitance in farads,  
In general the basic formulas
expressing total impedance are: 
R_{L} = 
resistance in ohms acting in
series with inductance, 

for series circuits,  R_{C} = 
resistance in ohms acting in
series with capacitance, 

= 
phase angle in degrees by which
current leads voltage in a capacitive circuit, or lags voltage in an inductive circuit. In a resonant circuit , where X_{L} equals X_{C}, equals 0^{o}. 

for parallel circuits,  
Degrees X 0.0175 = radians.
1 radian = 57.3^{o} 

See page 17 for formulas involving impedance, conductance, susceptance and admittance.  Numerical Magnitude of Impedance . . .  
of resistance alone  
Z = R  
= 0_{o}  
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