Ohm’s law behavior in a purely resistive circuit: If the applied voltage increases while resistance is constant, does the current increase as well?

Difficulty: Easy

Correct Answer: Yes — with R constant, I increases in direct proportion to V.

Explanation:


Introduction / Context:
Ohm’s law is foundational for DC and low-frequency AC analysis in resistive circuits. This question checks proportional relationships among voltage, current, and resistance.


Given Data / Assumptions:

  • Purely resistive element with constant resistance R (no reactive components).
  • Voltage V is varied; R is held constant.
  • Temperature changes are negligible so R does not drift.


Concept / Approach:
Ohm’s law states V = I * R. For a fixed R, current I = V / R, so I is directly proportional to V. Doubling V doubles I, and halving V halves I. This proportionality holds for both DC and AC at frequencies where the resistor’s behavior is ideal.


Step-by-Step Solution:

Start with V = I * R.Solve for current: I = V / R with R constant.Conclude: as V increases, I increases proportionally.


Verification / Alternative check:
Power relation P = V * I = V^2 / R shows power grows with the square of voltage at fixed R, consistent with I rising linearly with V.


Why Other Options Are Wrong:

  • Current unchanged (option b) contradicts I = V / R.
  • Current decreases (option c) reverses the dependence.
  • “Depends on power factor” (option d) is irrelevant in a purely resistive load where power factor is 1.


Common Pitfalls:
Ignoring that real resistors heat and change resistance slightly; within normal ranges, the ideal model is accurate for analysis.


Final Answer:
Yes — current increases with voltage when R is constant.

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