In a circuit, current is directly proportional to voltage and inversely proportional to what?

Current being directly proportional to voltage and inversely proportional to another quantity is a fundamental concept in electrical engineering, expressed by Ohm's Law, which states that I = V/R, where I is the current, V is the voltage, and R is the resistance. In this relationship, as voltage increases, current increases if resistance remains constant. Conversely, if resistance increases while voltage remains the same, the current decreases.

Resistance is a measure of how much a material opposes the flow of electric current. Thus, as resistance increases, the amount of current that can flow through the circuit decreases for a given voltage, which aligns with the principle that current is inversely proportional to resistance.

The other options (power, capacitance, and frequency) do not maintain this direct relationship with current in the context described. While each of them plays a role in electrical circuits, they do not fit the criteria of being inversely related to current with respect to a constant voltage. Hence, resistance is the correct choice for this relationship.