Question

the power factor of series R-L is given by​

Answer 1

Step-by-step explanation:The inductor in the circuit is offering a reactance (X) to the flow of current. Inductive reactance is calculated by X=2πfL, where f is the supply frequency and L is the inductance. The vector sum of this value and the value of resistance will give the impedance of the circuit, and the cosine of the angle between the resistance (x-axis) and reactance (y-axis), is the power factor.

Since there is only inductance in this example, the power factor will be lagging, i.e. the current will lag the voltage by the angle calculated above.