Basic concept check: Does electrical resistance limit or oppose the flow of current in a circuit?

Question

Accepted Answer

Introduction / Context: Resistance is one of the three primary electrical quantities along with voltage and current. Understanding its role is essential for designing safe and functional circuits. Given Data / Assumptions: Ohm’s law applies: V = I * R. Linear resistive behavior (no significant temperature or nonlinearity effects). Either DC or AC conditions at frequencies where resistive behavior dominates. Concept / Approach: For a given applied voltage, the current through a resistor is I = V / R. A larger R yields smaller I, demonstrating that resistance limits current. Physically, resistance converts electrical energy into heat (I^2R losses), representing opposition to charge flow due to collisions within the material lattice. Step-by-Step Solution: Start with V = I * R.Rearrange to I = V / R.Observe inverse relationship: increasing R reduces I for the same V. Verification / Alternative check: Measure a simple circuit: a fixed 9 V source with resistors of 100 Ω and 1 kΩ yields 90 mA and 9 mA respectively, confirming current is limited by resistance. Why Other Options Are Wrong: “Resistance increases current” (option b) inverts the relationship. “Resistance stores energy” (option c) confuses resistors with capacitors/inductors. “Only affects AC” (option d) is incorrect; Ohm’s law holds for DC as well. Common Pitfalls: Confusing resistance (opposition with dissipation) with reactance (opposition with energy storage). Both oppose current but in different ways. Final Answer: Yes — resistance limits current.

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