Final answer:
Current in a closed circuit flows from the positive to the negative terminal of the power source, through the electrical device, such as a lamp. This complete path is required for the current to flow and light the lamp, which is depicted in circuit schematics using standardized symbols.
Step-by-step explanation:
In a closed circuit, the current flows from the positive terminal of the power source (such as a battery) to an electrical device (like a lamp) and then back to the negative terminal of the power source. This flow of electric charge, which is called direct current (DC), occurs only when there is a complete path for the charge to move through. When a switch in the circuit is closed, this path is completed, allowing the current to flow, which in turn causes the lamp to illuminate. The components of a simple circuit, including the power source, connecting wires, switch, and the electrical device, are typically represented in a schematic, which uses standardized symbols to visualize the circuitry.
For instance, in a schematic, the battery is shown as a series of long and short parallel lines, the wires are represented by solid lines, the switch is illustrated as two points that can be connected by a conducting bar, and the lamp is denoted by a circle with a loop inside. When the switch is on, the current path is completed and current flows consistently in one direction—from the positive to the negative terminal, which is typical of DC currents.