What type of diagram uses symbols to represent electrical devices and how they are connected?

The correct answer is Schematic because a schematic diagram is specifically designed to illustrate the components of an electrical system and how they are interconnected. These diagrams use standardized symbols to represent different electrical devices, such as resistors, capacitors, and power sources, allowing for clear communication of the system's layout and functionality without requiring a detailed physical representation.

In contrast, pictorial diagrams tend to use realistic images to depict devices but do not convey the technical interconnections as clearly as schematics. Isometric diagrams aim to represent three-dimensional objects in two dimensions, which can be helpful for engineering designs but do not focus on the connections between electrical devices. Scaled diagrams refer to drawings that maintain a specific scale proportion but do not inherently imply the use of symbols or electrical conventions for representation. Hence, the use of schematic diagrams is essential for understanding and designing electrical circuits effectively.