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Topic: Electrical energy and power· Current Electricity

Six similar bulbs are connected as shown in the figure with a DC source of emf E, and zero internal resistance.The ratio of power consumption by the bulbs when (i) all are glowing and (ii) in the situation when two from section A and one from section…

Six similar bulbs are connected as shown in the figure with a DC source of emf E, and zero internal resistance.

The ratio of power consumption by the bulbs when (i) all are glowing and (ii) in the situation when two from section A and one from section B are glowing, will be :

circuit of six bulbs in sections A and B with battery E

1. 4 : 9

2. 9 : 4

3. 1 : 2

4. 2 : 1

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Answer: 2. 9 : 4

From the figure, the three bulbs of section A are in parallel with each other, as are the three bulbs of section B. The two sections are in series across the source.

Let each bulb have resistance \(R\).

  1. All six glowing: \(R_{eq}=\tfrac R3+\tfrac R3=\tfrac{2R}3\), so \(P_1=\dfrac{E^2}{2R/3}=\dfrac{3E^2}{2R}\).
  2. Two from A and one from B: \(R_{eq}=\tfrac R2+R=\tfrac{3R}2\), so \(P_2=\dfrac{2E^2}{3R}\).

\(P_1:P_2=\dfrac32:\dfrac23=9:4\).

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report
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