defination:
  1. Ratio of Active Power (P) to Apparent Power (S).
  2. Cosine of the Angle Between Voltage (V) and Current (I).
  3. Ratio of the Resistance (R) to the Impedance (Z) of the Circuit.
significance:
  1. If the PF is low, the Current Increases for the same Power, which increases the Resistive Losses, therby reducing the efficiency.