Final answer:
An arc flash is a dangerous electrical event that occurs when a spark jumps between conductors and ionizes the air, maintaining the current flow and potentially causing an explosion. High voltage circuit breakers use insulating gas or gas jets to blow out sparks to combat this. Electrical currents can have varied effects on the human body, from therapeutic to fatal. Therefore given statement is A
Step-by-step explanation:
An arc flash occurs when there is a high voltage breakdown of the resistance of air which leads to an arc of electricity between conductors. This can happen if a conductor goes to ground, potentially causing circuit breakers or fuses to blow due to the rapid increase in current. However, despite circuit breakers being designed to interrupt current flow to prevent damage, in high voltage situations a spark might jump across the breaker's contacts. This ionizes the surrounding air and maintains the conductive pathway, leading to continuous current flow and potential arc flash events.
In high voltage power-distribution systems, specialized equipment such as circuit breakers filled with insulating gas or that utilize gas jets to blow out sparks are used to mitigate this issue. This is particularly important as alternating current (AC) is considered safer in such environments because it repeatedly goes through zero voltage, which provides frequent opportunities to quell any arcs compared to direct current (DC) that does not have this feature.
Shock hazards are a significant concern associated with electrical currents. Currents can vary in effect when they pass through the human body, from therapeutic uses like blocking back pain to causing fatal ventricular fibrillation. Special medical devices such as pacemakers and defibrillators use controlled electric shocks to maintain or restore regular heart rhythm, respectively.