From the impedance triangle of an R-L series circuit fed with single-phase voltage, what is the value of power factor of the circuit?

Concept:

• Power factor (PF) is the ratio of working power, measured in kilowatts (kW), to apparent power, measured in kilovolt amperes (kVA). 
• The triangle that is created when adding the resistance to the reactance is known as an impedance triangle
• ​The power factor has also been defined as the ratio between resistance and impedance

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Hence the power factor is Cos ϕ = \(R \over Z\)