In an electric circuit, what does resistance oppose?

In an electric circuit, resistance specifically opposes the flow of electric current. Resistance is a measure of how much a material impedes the movement of electrons, which constitutes the current in an electrical circuit. When resistance is present, it restricts the amount of current that can flow through the circuit for a given voltage, as described by Ohm's Law (V = IR, where V is voltage, I is current, and R is resistance).

While voltage, power, and frequency are important concepts in electricity, they do not directly relate to what resistance opposes. Voltage represents the potential difference that drives current; power is the rate at which energy is used or generated, and frequency pertains to the number of cycles of alternating current per second. Therefore, the key role of resistance in an electric circuit is its opposition to current flow.