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Question: Answered & Verified by Expert
The internal resistance of a $2.1 \mathrm{~V}$ cell which gives a current of $0.2 \mathrm{~A}$ through a resistance of $10 \Omega$ is
PhysicsCurrent ElectricityNEETNEET 2013 (All India)
Options:
  • A $0.2 \Omega$
  • B $0.5 \Omega$
  • C $0.8 \Omega$
  • D $1.0 \Omega$
Solution:
1743 Upvotes Verified Answer
The correct answer is: $0.5 \Omega$
\(\begin{aligned} & I=\frac{E}{R+r} \\ & 0.2 \times(10+r)=2.1 \\ & 10+r=\frac{2.1}{2} \times 10 \\ & r=10.5-10=0.5 \Omega\end{aligned}\)

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