Why are two conducting paths from a voltage source to an electrical device needed to operate the device?

In electrical circuits, a voltage source (typically a battery) pushes electrons in a loop, resulting in electric phenomena like sound and light.

We can divide a complicated circuit into two parts: a voltage source and an electrical or electronic device.

A wall socket (voltage source) and a fan are two examples (device).

When we connect electrical equipment to a battery, we're not merely releasing electrons into the device, and we need two wires. The electron needs to return to the battery's positive terminal.

As a result, electrons must travel in a full circuit and return to their starting point. If this were not the case, negative charges would collect in one location while positive charges would accumulate in another.