Standard Science Primary 5 Systems

Alexa has a circuit with one battery and two bulbs in series. If she adds a third identical bulb in series, what will happen to the brightness of the bulbs?

A They will fuse immediately.
B They will become brighter.
C Their brightness will remain the same.
D They will become dimmer.
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Worked Solution

Step 1: In a series circuit, the electrical energy provided by the battery is shared among the components. Step 2: Adding a third bulb increases the resistance in the single pathway. Step 3: The electrical energy must now be shared among three bulbs instead of two, causing them to light up less brightly.

Correct answer: They will become dimmer.

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