What does it mean for a circuit to be "closed"?

A circuit being described as "closed" means that it is complete, allowing electrical current to flow through it without interruptions. When all components in a circuit—like the power source, wires, and load—are connected in a continuous path, electrical current can move freely. This is essential for the operation of electrical devices, as they depend on that uninterrupted flow of current to function properly.

The concept of a closed circuit is fundamental in electrical systems. When you flip a switch to the "on" position, for instance, you are effectively closing the circuit, enabling appliances or lights to operate.

In contrast, if a circuit is incomplete, meaning there’s a break somewhere or it's not correctly closed, no current will flow, resulting in a non-functioning circuit. Understanding this fundamental distinction helps in troubleshooting and circuit design, making the concept of a closed circuit very important in electrical work.