What is the main difference between AC and DC currents?

The primary distinction between AC (alternating current) and DC (direct current) lies in their flow characteristics. AC changes direction periodically, flowing back and forth in a circuit, typically at a frequency of 50 or 60 hertz, depending on the region. This alternating flow allows for the easy transformation of voltage levels, facilitating efficient long-distance power transmission.

On the other hand, DC flows in one constant direction only, maintaining a steady voltage level. This type of current is often used in batteries, electronics, and applications where a stable and consistent voltage is required.

The other options suggest incorrect relationships or applications of AC and DC. For instance, while there are specific uses for both types of current, it's not accurate that one is exclusively for residential and the other for commercial applications. Safety considerations also vary based on specific circumstances rather than a blanket difference in safety between AC and DC for household use.