A power factor of 1.0 indicates:

SOLUTION

• 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.

          Power factor = cos ϕ

          ϕ is the angle between the voltage and the current.

• For a purely resistive circuit, the angle between the voltage and current is 0°

          So power factor for a purely resistive circuit is:

          P.F. = cos 0° 

          P.F. = 1 (unity)

• In a purely inductive circuit, the current lags the voltage by 90° and the power factor is lagging.
• In a purely capacitive circuit, the current leads the voltage by 90° and the power factor is leading.