Final answer:
The input power factor of a single-phase half-wave rectifier supplying a purely resistive load is 1, indicating no phase shift between current and voltage.
Step-by-step explanation:
The input power factor of a single-phase half-wave rectifier supplying a resistive load can be considered to be 1 (or unity) because a purely resistive load does not introduce a phase shift between current and voltage. Unlike in RLC circuits where inductors and capacitors create phase shifts resulting in power factors that range between -1 and 1, in a resistive circuit, the voltage and current are in phase. So, even though a half-wave rectifier will introduce pulses in the current waveforms, the power factor is still considered to be 1 if the load is purely resistive; harmonics are undoubted resulting from the rectification process but do not affect the power factor of the resistive component.