Aging effects — if the resistance value of one branch in a parallel network drifts with age, which electrical quantity in that branch changes as a direct consequence (assuming the supply voltage remains regulated)?

Introduction / Context:
Real components age, and resistors can drift upward or downward in value. In a parallel network supplied by a regulated source, it is important to predict which quantities change when one branch’s resistance changes over time.

Given Data / Assumptions:

• Parallel branches share the same two nodes (common voltage).
• Supply is ideal or well-regulated; bus voltage stays approximately constant.
• Only one resistor’s value drifts; others remain nominal.

Concept / Approach:
In parallel, the voltage across each branch equals the supply bus voltage. Ohm’s law in the drifting branch is I_branch = V_bus / R_branch. If R_branch changes while V_bus is held constant, then I_branch must change inversely with R_branch, while the branch voltage remains essentially the same as the bus voltage.

Step-by-Step Solution:

Verification / Alternative check:
You can model the network as a Norton equivalent seen by the branch. With a stiff source (low source resistance), branch voltage is fixed and branch current follows Ohm’s law with the changed resistance.

Why Other Options Are Wrong:

• Branch voltage: In parallel with a regulated source, voltage is essentially constant.
• Both branch current and branch voltage: Voltage is stable; only current changes markedly.
• Power supply voltage: A regulated source maintains voltage independent of single-branch drift.

Common Pitfalls:
Assuming that any change in a component forces the supply to change voltage; with proper regulation, current changes while voltage stays fixed.

Final Answer:
Branch current changes when a parallel resistor’s value drifts (with the bus voltage held constant).