Final answer:
In IFC therapy, a dynamic vector refers to the movement of the location where the two crossing currents intersect throughout the treatment field, enhancing stimulation over a larger area.
Step-by-step explanation:
When using Interferential Current (IFC) therapy, if the location where the two currents cross moves throughout the treatment field, it is called a dynamic vector. The two overlapping currents interfere with each other, and the interference pattern can be manipulated so that the point of maximum intensity moves in a predictable manner. This method is often used to cover a larger treatment area or to provide a more stimulating effect than static application might provide.