A cell of internal resistance r drives current through an external resistance R . The power delivered by the…

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:
  1. R=2r
  2. R=r
  3. R=1000 r
  4. R=0.001 r

Solution

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

Asked in: JEE Main 2019 (08 Apr Shift 2)

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