GMAS 8th Grade Science Practice Test

A circuit is a closed loop that allows electric current to flow from a power source through conductors and components and back to the source. The loop must be continuous, because current only moves when there is a complete path; if a switch is open or a wire is broken, the current stops. This idea helps explain why energy can be delivered to lights, motors, sensors, or other devices—the energy is carried around the loop and used by the components along the way. Storing charge isn’t what defines a circuit (storage happens in devices like capacitors, which are parts of circuits but not the definition itself). And a circuit isn’t limited to converting energy to heat; it can power many different loads. A simple setup with a battery and a resistor is indeed a basic circuit, but the essential concept is the complete loop that allows current to flow through the entire path.