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Question: Answered & Verified by Expert
An electric bulb of 500 W at 100 V is used in a circuit having a 200 V supply. Calculate the resistance R to be connected in series with the bulb so that the power delivered by the bulb is 500 W.
PhysicsCurrent ElectricityJEE MainJEE Main 2021 (26 Aug Shift 2)
Options:
  • A 30 Ω
  • B 5 Ω
  • C 20 Ω
  • D 10 Ω
Solution:
2725 Upvotes Verified Answer
The correct answer is: 20 Ω

Resistance of bulb

P=V2r

r=(100)2500=100×100500=20

i=PV=500100=5 A

ΔV in resistance R=100 V

R=1005=20 Ω

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