Which property of a conductor opposes current flow?

Resistance is the property of a conductor that opposes the flow of electric current. It arises due to collisions between the moving charge carriers (usually electrons) and the atoms in the conductor, which converts some of the energy into heat. The amount of resistance in a material is determined by its physical properties, such as length, cross-sectional area, and the type of material itself. For example, longer conductors and those with smaller cross-sectional areas typically exhibit higher resistance.

In electrical circuits, this resistance dictates how much current will flow for a given voltage according to Ohm's Law, which states that current is equal to voltage divided by resistance (I = V/R). Higher resistance means lesser current for a given voltage, illustrating its opposing effect on current flow. Thus, the role of resistance is fundamental in controlling and managing the behavior of electrical systems and devices.