ALLIED'S ELECTRONICS DATA HANDBOOK

Most Used Formulas (cont.)

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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,
  XL  =   inductive reactance in ohms,     R  =   resistance in ohms,
  XC  =   capacitive reactance in ohms,     X  =   reactance (inductive or
 capacitive) in ohms,
  RL  =   resistance in ohms acting in series
 with inductance,
  Nomenclature
  RC  =   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 a-c 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:
    XL  =   inductive reactance in ohms,
    XC  =   capacitive reactance in ohms,
    L  =   inductance in henrys,
    C  =   capacitance in farads,
   In general the basic formulas expressing total
 impedance are:
    RL  =   resistance in ohms acting in
 series with inductance,
 for series circuits,     RC  =   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
 XL equals XC, equals 0o.

for parallel circuits,  
        
       Degrees X 0.0175 = radians.
 1 radian = 57.3o
   See page 17 for formulas involving impedance, conductance, susceptance and admittance.   Numerical Magnitude of Impedance . . .
   
     of resistance alone
                               Z = R
                              = 0o
             

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