Two identical cells gave the same current through an external resistance of $2 \Omega$ regardless whether the cells are grouped in series or parallel. The internal resistance of the cells is

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Aicharya · Accepted Answer

For first case, $I=\frac{2 E}{R+2 r}$...(i)

For second case, $I=\frac{E}{R+\frac{r}{2}}=\frac{2 E}{2 R+r}$....(ii)

From eqs(i) and (ii), we get $\mathrm{R}+2 \mathrm{r}=2 \mathrm{R}+\mathrm{r} \Rightarrow \mathrm{r}=\mathrm{R}=2 \Omega$

Two identical cells gave the same current through an external resistance of $2 \Omega$ regardless whether…

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