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Two electric lamps of each 40 watt are connected in series. The power consumed by the combination will be -

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Question

Two electric lamps of each 40 watt are connected in series. The power consumed by the combination will be

Options

  • 20 Watt

  • 60 Watt

  • 80 Watt

  • 100 Watt

MCQ

Solution

20 Watt

Explanation:

Each bulb's resistance = V2/40 ohm.

Total resistance of two bulbs connected in series

R = `V^2/40 + V^2/40 = V^2/20`

As a result, the effective power of two bulbs is

R = `V^2/R = V^2/(V^2/20)` = 20 watt

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