JEE Mains · Physics · STD 12 - 3. current electricity
Two identical cells, when connected either in parallel or in series gives same current in an external resistance \(5\,\Omega\). The internal resistance of each cell will be \(.............\,\Omega\).
- A \(5\)
- B \(4\)
- C \(3\)
- D \(2\)
Answer & Solution
Correct Answer
(A) \(5\)
Step-by-step Solution
Detailed explanation
\(i=\frac{2 \varepsilon}{5+2 r}........(1)\) \(i=\frac{\varepsilon}{\frac{r}{2}+5}.........(2)\) Equating \((1)\) and \((2)\) \(\frac{2 \varepsilon}{5+2 r }=\frac{\varepsilon}{\frac{ r }{2}+5} \Rightarrow r +10=5+2 r\) \(r=5\) Ans.\(5\)
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