Practice question · Multiple choice
Three identical bulbs: A is in series with the battery; the pair B and C are in parallel with each other after A. If bulb C burns out (breaks the branch), what happens to bulb A?
Hints
- Removing C leaves B alone where the parallel pair used to be. Does the branch resistance rise or fall?
- A parallel pair of equal resistors has half the resistance of one alone. Total series resistance therefore increases when C dies.
Show the answer
A. A gets dimmer: total resistance rose
Why
Losing C turns the parallel pair () into a single bulb (), raising the loop resistance from to . The battery pushes less current, so A dims, while B, now receiving the full branch current, actually brightens.
Practise Kirchhoff's Laws and Circuit Analysis
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