Parallel bulbs: when one burns out
Two identical bulbs are connected in parallel to an ideal battery. One bulb burns out. What happens to the other?
Answer C: explanation for every choice
A
A bulb goes out when the circuit is broken, as in a series circuit. Here its branch stays complete.
B
Its voltage and current don't change, so its brightness doesn't change.
C
Correct. Each parallel branch has the full battery voltage across it independently, so the other bulb is unaffected.
D
The voltage across it stays the same.
TakeawayParallel branches each get the full voltage. Series elements share one current path.
Next question →
Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID cp79.