What is defined as a conducting path from the positive terminal to the negative terminal of a power source?

A circuit is defined as a conducting path that allows electric current to flow from the positive terminal to the negative terminal of a power source. In the context of electricity, a circuit typically includes not only the power source, such as a battery or generator, but also the connections and components that facilitate the flow of electrons, completing the loop necessary for current to move. This definition is fundamental to understanding how electrical systems operate, as a complete circuit is required to power devices or perform useful work.

The other terms mentioned serve different purposes. A battery is a type of power source that converts stored chemical energy into electrical energy. A conductor refers to a material, often a wire, which allows electric current to flow through it but does not by itself denote a complete circuit. A transistor is a semiconductor device used to amplify or switch electronic signals, and it is an integral component, not a path for current flow. Thus, the comprehensive understanding of the term circuit in the context of power flow makes it the correct choice.