WBJEE · Physics · Current Electricity
Two cells with the same e.m.f. \(E\) and different internal resistances \(r_1\) and \(r_2\) are connected in series to an external resistance \(R\). The value of \(R\) so that the potential difference across the first cell be zero is
- A \(\sqrt{r_1 r_2}\)
- B \(r_1+r_2\)
- C \(\mathrm{r}_1-\mathrm{r}_2\)
- D \(\frac{r_1+r_2}{2}\)
Answer & Solution
Correct Answer
(C) \(\mathrm{r}_1-\mathrm{r}_2\)
Step-by-step Solution
Detailed explanation
Hints: \(I=\frac{2 E}{R+r_1+r_2}\) Potential difference across first cell \(\mathrm{V}=\mathrm{E}-\mathrm{Ir}_1=0\)…
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