What visual representation indicates positive voltage in TPC schematics?

In TPC schematics, the use of red lines is a conventional representation associated with positive voltage. This color-coding is widespread in electrical and electronic schematics, as it provides an immediate visual cue to the viewer that the circuit is conducting positive electrical potential. The red line's prominence and recognition in various practices help engineers and technicians quickly identify potential sources of voltage within a circuit.

Using color coding like red for positive voltage enhances readability and aids in troubleshooting, allowing anyone examining the schematic to follow paths of current flow more intuitively. Other visual representations in the choices provided, such as blue dash lines, green solid lines, and yellow circles, are typically used for different purposes or denote other aspects of the circuit, making them unsuitable for indicating positive voltage.