What characterizes an electric arc?

An electric arc is characterized by a visible plasma discharge that occurs between two electrodes due to the presence of electrical current. This phenomenon happens when the voltage across the electrodes becomes high enough to ionize the air (or another medium) between them, allowing current to flow in a conductive plasma form. The resulting arc can produce intense heat and light, which is why it is often visible and can be very striking.

In the context of electrical engineering, knowing how arcs form and behave is essential, particularly when designing circuits that may be susceptible to arcing, such as in switches, breakers, and certain types of loads. This understanding helps in implementing safety measures to prevent damage or dangerous situations caused by unintended arcing.

Other options do not define an electric arc. A sudden loss of power refers to a circuit failure or interruption, a continuous flow of current indicates steady-state conduction, and a measure of electrical resistance relates to the opposition of current flow in a circuit, none of which properly describe the unique phenomenon of an electric arc.