Standard Science Primary 5 Systems

Study the circuit diagram below. Which bulb(s) will light up when only Switch S1 is closed?

A Only B1
B Neither B1 nor B2
C Both B1 and B2
D Only B2
Show Worked Solution

Worked Solution

Step 1: Identify the circuit as a parallel arrangement. Step 2: Switch S1 is in series with Bulb B1 on the top branch. Step 3: Closing S1 completes the path for current to flow through B1 only. Step 4: Bulb B2 remains in an open circuit because its branch is not controlled by S1.

Correct answer: Only B1

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