Power factor is only related to the AC circuit.DC circuit will not have power face since there is zero frequency and phase angle difference between current and voltage.
Power Factor is given by the cosine of the angle between voltage and current
P =VI Cosθ
Rearranging the above formula we get
Cosθ = True Power/Apparent Power
Cosθ = Power factor
P = Power in Watts
V = Voltages in Volts
I = Current in Amperes
The true power is given in terms of Watts and the Apparent power is given in terms of Volt-Amperes or Watts
The power factor in an AC circuit is also given by the ratio of Resistance and Impedence
R = Resistance in ohms
Z = Impedance
Impedance (Z) is the total resistance in the AC circuit and is given by
R = resistance
XL =inductive reactance
Xc = capacitive reactance
Here, it is noted that single phase power factor is less than 1.
Note: For a purely resistive circuit, the power factor is 1.
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