Definition
A complete path through which electric current can flow, consisting of a power source, conductors, a load (the device being powered), and usually a control device such as a switch and a protective device such as a fuse or circuit breaker. The path must be unbroken for current to flow.
Plain English
A loop that lets electricity travel from a power source, through wires, to something it powers, and back again. If the loop is broken anywhere, the electricity stops flowing.
Context Anchor
Seen in aircraft electrical system descriptions, troubleshooting steps, wiring diagrams, and maintenance checks.
Derivation
From Latin 'circuitus,' meaning 'a going around.' The word captures the key idea: electricity must travel a complete loop, leaving the source and returning to it, for the circuit to work.
Why Pilots Care
A break or fault in an electrical circuit can disable radios, instruments, lights, or other systems essential for safe flight and ground operations.
Analogy
Think of a circuit like a closed loop of road. Cars can keep moving only if the road goes all the way around; if a bridge is out, traffic stops at the break.
Intuition Check
Do not think of an electrical circuit as just a wire. In aircraft use, it means the whole usable path: power source, wires, the device using the power, controls or protection, and the return path.
Example Sentence 1
When the landing light switch is closed, it completes the electrical circuit and the lamp turns on.
Example Sentence 2
A loose connection in the electrical circuit caused the cockpit annunciator lights to flicker during preflight.