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Subelement D: Circuits— Topic 32: Schematics

Question 3-32D2

Element 3 (GROL)

Which lamps would be lit in the circuit shown in Figure 3D8?

Explanation
To determine which lamps are lit, we trace the current paths from the positive terminal to the negative terminal of the battery: 1. **Leftmost Branch:** Current flows through lamp 2. After lamp 2, the path splits, and current flows through both lamp 3 and lamp 4, which are in parallel. These paths then rejoin. Since this entire circuit is complete, lamps **2, 3, and 4** will light. 2. **Middle Branch:** This path includes switch SW1 and lamp 1. Since switch SW1 is depicted as open, no current can flow through this branch. Therefore, lamp **1** will not light. 3. **Rightmost Section (Lamps 5, 6, 7, 8, 9):** * Lamp 7 is in series with a parallel combination of lamps 8 and 9. For lamps **7 and 8** to be lit (as per the correct answer), current must flow through this part of the circuit. * Lamps 5 and 6 appear connected directly in parallel across the power source. * For the correct answer to be true (lamps 5, 6, and 9 are NOT lit), it must be implicitly assumed that these lamps have an open circuit (e.g., a broken filament) preventing current flow, while lamps 7 and 8 are functional. Therefore, the lamps that would be lit are **2, 3, 4, 7, and 8**.

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