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Question: Answered & Verified by Expert
A cell of internal resistance r drives current through an external resistance R. The power delivered by the cell to the external resistance will be maximum when:
PhysicsCurrent ElectricityJEE MainJEE Main 2019 (08 Apr Shift 2)
Options:
  • A R=2r
  • B R=r
  • C R=1000 r
  • D R=0.001 r
Solution:
2255 Upvotes Verified Answer
The correct answer is: R=r

Current i=Er+R
Power generated in R

P=i2R
P=E2R(r+R)2

for maximum power dPdR=0
E2(r+R)2×1-R×2(r+R)(r+R)4=0
when, r=R then, dPdR=0

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