Component failure modes — fixed resistors: Assess the statement: “Fixed-value resistors can internally short-circuit.”

Introduction / Context:
Understanding typical and atypical failure modes of passive components helps technicians diagnose faults efficiently. While open-circuit failures are more common for resistors, short-circuit failures, though rarer, can occur and carry serious risk for downstream circuitry.

Given Data / Assumptions:

• Resistor types considered: carbon film, metal film, thick/thin film, wirewound, carbon composition.
• Operating in realistic environments with possible surge, overheating, or contamination.
• We are discussing failure possibilities, not probabilities.

Concept / Approach:
Resistors can fail open due to element cracking or fusing. Shorts can result from carbonization of encapsulant after severe overheating, melted or collapsed spacing between turns in wirewound devices, conductive residue bridging terminations, or moisture ingress creating low-resistance paths. Though statistically less frequent than opens, shorts are a legitimate failure mode acknowledged by manufacturers and failure analysis reports.

Step-by-Step Solution:

Verification / Alternative check:
Field reliability data and failure-analysis photos often show charred bodies with measurable low resistance across leads after over-stress—a practical demonstration of short failure modes.

Why Other Options Are Wrong:

• Incorrect: Ignores documented short mechanisms.
• True only for certain types or ratings: While mechanisms vary, shorts are not exclusive to a single type or power rating.
• Depends solely on humidity: Moisture is one factor, not the only cause.

Common Pitfalls:
Assuming a resistor “can only go open.” This bias can lead to missed diagnoses when a supply rail is unexpectedly pulled low by a failed resistor.

Final Answer:
Correct