Advanced Science Primary 5 Systems

In a parallel circuit with three bulbs (B1, B2, B3) and three switches (S1, S2, S3), which switch must be closed for only Bulb B2 to light up?

A S1 only
B S1, S2 and S3
C S1 and S2
D S2 only
Show Worked Solution

Worked Solution

Step 1: In a parallel circuit, each branch can be controlled independently. Step [2-9]: If each bulb has a switch on its branch, closing only S2 completes the path for B2. Step [2-9]: Other branches remain open, so B1 and B3 stay off.

Correct answer: S2 only

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