An arc is a discharge of electricity through a gas, such as air, between two electrodes. This discharge can be produced by either AC (alternating current) or DC (direct current) electrical power sources.
In AC circuits, the direction of the current changes periodically, which causes the arc to flicker and oscillate rapidly. This can create a buzzing sound and can be more difficult to control than a DC arc.
In DC circuits, the current flows in one direction only, which can create a more stable and predictable arc. DC arcs are commonly used in welding applications because they provide a steady heat source and are easier to control.
Overall, the choice between AC and DC current for arc production depends on the specific application and the desired properties of the arc.