DC CIRCUIT ANALYSIS Basic DC Theory Clear the fraction so that we have a common denominator: 4V_N 3 (60 V_N) 6 (20 V_N) 4V_N 180 3V_N 120 6V_N 13V_N 300 V_N 23.077 Third, find all voltage drops and currents. V₁ V_A V_N 60 23.077 36.923  Volts V₂ V_N 23.077  Volts V₃ V_B V_N 20 23.077 3.077  Volts The  negative  value  for  V₃  shows  that  the  current  flow  through  R₃  is  opposite  that  which  was assumed and that the polarity across R₃ is reversed. I₁ V₁ R₁ 36.923  V 8W 4.65  amps I₂ V₃ R₃ 3.077  V 4W 0.769  amps I₃ V₂ R₂ 23.077  V 6W 3.846  amps The  negative  value  for  I₃  shows  that  the  current  flow  through  R₃  is  opposite  that  which  was assumed. Series-Parallel Circuit Analysis When  solving  for  voltage,  current,  and  resistance  in  a  series-parallel  circuit,  follow  the  rules which apply to the series part of the circuit, and follow the rules which apply to the parallel part of  the  circuit.    Solving  these  circuits  can  be  simplified  by  reducing  the  circuit  to  a  single equivalent  resistance  circuit,  and  redrawing  the  circuit  in  simplified  form.   The  circuit  is  then called an equivalent circuit (Figure 46). ES-02 Page 58 Rev. 0