In electrical circuits, what does resistance measure?

Resistance in electrical circuits specifically measures the opposition to electrical flow. This means that when an electrical potential (voltage) is applied across a conductor, the resistance determines how much current will flow through the conductor. A higher resistance indicates that it is more difficult for the electrical current to flow, while a lower resistance means an easier flow of current.

Understanding resistance is crucial because it directly influences the efficiency and functionality of electrical devices. It plays a significant role in Ohm's Law, which states that the current (I) passing through a conductor between two points is directly proportional to the voltage (V) across the two points and inversely proportional to the resistance (R). Thus, where resistance is high, the current flow is minimized, affecting power consumption and circuit behavior.

In contrast, the other options focus on different aspects of electrical circuits: ease of flow relates to conductivity rather than resistance, power consumption is a product of voltage and current (and influenced by resistance but not its measure), and voltage describes the potential difference that drives current through a circuit, not the opposition to that flow.