What is meant by resistance in an electrical circuit?

• A. The force that drives electrons
• B. The energy supplied by the source
• C. The rate of energy transfer
• D. Opposition to the flow of electrons

Answer: (D)

Resistance is the opposition to the flow of electric charges in a component or circuit. For a given voltage across something, higher resistance means less current flows, described by Ohm’s law I = V/R (so increasing resistance lowers current). Resistance arises from how easily electrons collide with atoms in the material and lose energy as heat; it depends on material, temperature, length, and cross-sectional area. Because of this opposition, resistive elements dissipate electrical energy as heat, with power related by P = I^2R = V^2/R. The force that drives electrons is the voltage, not resistance, and the energy supplied by the source is tied to voltage; the rate of energy transfer is power, not resistance.