Standard Science Primary 5 Systems

Ravi has a circuit with one battery and one bulb. He adds another identical bulb in series. What will he observe about the brightness of the bulbs?

A Both bulbs will be brighter than the original single bulb.
B Both bulbs will be dimmer than the original single bulb.
C There will be no change in brightness.
D The first bulb will be bright, and the second will be dim.
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Worked Solution

Step 1: In a series circuit, adding more bulbs increases the total resistance. Step 2: The electrical energy from the single battery must now be shared between two bulbs. Step 3: Consequently, less electrical energy flows through each filament, making them dimmer.

Correct answer: Both bulbs will be dimmer than the original single bulb.

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