Which term is related to the graphical representation of electric quantities using phase relationships?

The term that specifically relates to the graphical representation of electric quantities using phase relationships is the phasor diagram. Phasor diagrams are used predominantly in electrical engineering to represent the sinusoidal voltages and currents as rotating vectors, or phasors. Each phasor has a magnitude and an angle that indicates its phase relative to a reference point, which effectively illustrates how different electrical quantities relate to each other in time and phase.

This representation is crucial for analyzing alternating current (AC) circuits, where voltages and currents vary sinusoidally. By using phasors, engineers can easily visualize and calculate the effects of phase differences in AC systems, simplifying complex problems into manageable graphical forms.

Other options might also deal with graphical representations, but they do not specifically emphasize the phase relationship aspect that phasor diagrams address. For instance, a graphical analysis could refer to various methods of visually interpreting data, while circuit diagrams illustrate the actual components and connections within an electric circuit. Vector diagrams, while related, are typically broader and do not solely focus on electric quantities or their phase relationships.