Correct Answer - Option 2 : unity
Concept:
The overall power factor is defined as the cosine of the angle between the phase voltage and phase current.
In AC circuits, the power factor is also defined as the ratio of the real power flowing to the load to the apparent power in the circuit.
Hence power factor can be defined as watts to volt-amperes, i.e.
Power factor = cos ϕ
ϕ is the angle between the voltage and the current.
For a purely resistive (DC) circuit, the angle between the voltage and current is 0°. ∴ The power factor for a purely resistive circuit is:
P.F. = cos 0°
P.F. = 1 (unity)
Important Points:
- In a purely inductive circuit, the current lags the voltage by 90° and the power factor is zero lagging
- In a purely capacitive circuit, the current leads the voltage by 90° and the power factor is zero leading
