Arc is defined as the flow of a high amount of current across an insulating medium, like air.

• A. Ground fault
• B. Arc
• C. Short circuit
• D. Load

Answer: (B)

An arc is a discharge where current flows across an insulating medium, like air, by ionizing it and creating a conductive path between conductors or to ground. When the air becomes ionized, it turns into plasma and lets a high current jump across the gap. That specific situation—current traveling through a medium that normally insulates—is what the term arc describes. Ground faults involve current finding an unintended path to earth but aren’t defined by crossing an air gap. A short circuit is a very low-impedance connection between supply and return (often a direct metal path), not necessarily described as flowing across air. A load is simply a device that consumes power, not a fault. So the description matches arc.