Parallel lamps on a constant-voltage source: Three lamps are in parallel across 120 V. If one lamp burns out (opens), how do the other two behave?

Introduction / Context:
Parallel connections ensure that each load sees the full source voltage independently of other parallel loads. Understanding this behavior is crucial for household wiring, automotive lighting, and fault analysis in distribution systems.

Given Data / Assumptions:

• Three lamps connected in parallel to a 120 V source.
• One lamp burns out, effectively becoming an open circuit.
• Assume the source holds 120 V and wiring resistance is negligible.

Concept / Approach:

In a parallel circuit, each branch is directly across the source. If one branch opens, the remaining branches are still connected to the same supply voltage; their currents and brightness (for identical lamps) remain unchanged, provided the source voltage is regulated.

Step-by-Step Solution:

Verification / Alternative check:

Compare to series circuits: in series, one open extinguishes all loads. In parallel, opens only affect the failed branch; the rest are unaffected if the supply is stiff.

Why Other Options Are Wrong:

Brighter or dimmer would imply a voltage change across the remaining lamps, which does not occur in a proper parallel setup. 'Will not light' describes series behavior, not parallel.

Common Pitfalls:

Confusing series and parallel effects; assuming supply droop under load—here we consider an ideal or well-regulated source.

Final Answer:

the remaining two will glow with the same brightness as before