When a circuit comprises only resistance, what will be the nature of its power factor?

When a circuit consists solely of resistance, the power factor will be high and in phase. The power factor is a measure of how effectively electrical power is being converted into useful work output and is expressed as the cosine of the phase angle between the voltage and current waveforms.

In a purely resistive circuit, the voltage and current are perfectly aligned, meaning they reach their peak values at the same time. This alignment indicates that all the power is being used effectively to do work (like heating elements or incandescent light bulbs), resulting in a power factor of 1 (or 100%).

A high power factor indicates efficient utilization of electrical power, while being "in phase" signifies that there is no reactive power component present, which typically occurs in circuits with inductance or capacitance. In summary, a resistive circuit achieves maximum efficiency with a power factor that is both high and in phase due to the direct relationship between voltage and current.