Which term is used to define a lack of electrical potential difference in a system?

The term that defines a lack of electrical potential difference in a system is "Equipotential." In an equipotential system, all points within the system have the same electric potential, meaning there is no voltage difference between those points. This concept is crucial in understanding how electric fields behave; in such systems, charge does not flow from one point to another because there is no incentive for movement due to a potential difference.

In the context of EEG and neurophysiology, recognizing equipotential conditions is important when interpreting electrical signals, as they can indicate areas of uniform electrical activity without gradients that might suggest the presence of a stronger voltage or current flow.

Other terms, like phase cancellation, total current, and static potential, refer to different concepts within physics and electrical engineering. Phase cancellation deals with waveform interactions, total current refers to the sum of currents in a circuit, and static potential usually implies a potential difference that remains constant with time but does not specify the absence of difference as effectively as equipotential does.