Harmonics cause undesired current on electrical systems, leading to overheating. Which term describes this current?

• A. Voltage
• B. Secondary
• C. Current
• D. Transient

Answer: (C)

Harmonics are distortions in the current waveform caused by non-linear loads, showing up as extra current components at harmonic frequencies. The heating in conductors and equipment comes from current flowing through resistance, which is proportional to I^2R losses, so the undesired effect is described by the current itself. Voltage is the driving force, not the quantity that directly causes heating. A transient refers to a short-lived spike, not a sustained harmonic content, and secondary is not a type of current. So the term that describes this undesired effect is current.