Which type of diagram shows how the circuit functions?

A schematic diagram is designed specifically to illustrate the operation and functionality of a circuit. It uses standardized symbols to represent electronic components such as resistors, capacitors, and transistors, allowing engineers and technicians to understand how a circuit is structured and how it operates. Each symbol conveys specific information about the component's function and interconnections, making it a crucial tool for analyzing and troubleshooting electrical systems. By presenting the circuit in a simplified manner, a schematic effectively communicates the logical flow of electricity and how various components work together to achieve a particular purpose.

In contrast, pictorial diagrams provide a more visually intuitive representation of components, often resembling how they appear physically, but they do not adequately convey functional relationships. Flowcharts are used to represent processes and sequences in logical tasks or decision-making processes, rather than electrical circuits. Circuit board layouts show the physical arrangement of components on a printed circuit board, focusing on spatial considerations rather than the functional operation of the circuit itself. Thus, the schematic is the most appropriate choice for illustrating how a circuit functions.