🔍 Key Concepts

• Behavior of switch-mode power supplies (SMPS) on AC mains • Relationship between harmonic content and current waveform shape • How power factor is affected by non‑sinusoidal currents

💭 Think About

• Think about whether an SMPS draws current smoothly over the entire AC cycle, or in short pulses near the voltage peaks. • If current is drawn in short pulses, what does that do to harmonic content: does it increase or decrease the number of frequency components besides the fundamental? • How does a highly distorted, peaky current waveform affect the power factor compared to an almost pure sine wave current at the same voltage?

✅ Before You Answer

• Review that high harmonic content usually comes from distorted or pulsed current waveforms. • Recall that ideal power factor (near 1) occurs when voltage and current are both sinusoidal and in phase. • Decide whether a typical, uncorrected SMPS input looks more like an ideal resistive load or a nonlinear, pulsed load and match that to the choice describing its harmonics and power factor.