What defines a high impedance circuit?

A high impedance circuit is characterized primarily by low current and high voltage. In such circuits, the impedance (essentially resistance to the flow of electric current) is high, which means that the circuit tends to limit the amount of current that flows through it.

Impedance is a measure of how much the circuit resists the flow of electrical current. When a circuit has high impedance, very little current is allowed to flow for a given voltage. This is commonly seen in circuits where components are designed to work with minimal current flow, such as in electronic signal processing applications.

In contrast, a low impedance circuit would allow a larger flow of current for the same amount of voltage, which is not the case for high impedance circuits. Additionally, saying that current and voltage are equal does not accurately represent the relationship that defines high impedance. Therefore, the choice indicating low current with high voltage effectively captures the essence of a high impedance circuit.