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10 identical cells each potential $E$ and internal resistance $r$ are connected in series to form a closed circuit
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Verified Answer
The correct answer is:
$3 E$
According to given situation, total voltage of 10 cells $=10 E$
Total resistance of 10 cells $=10 \mathrm{r}$
$\therefore$ Current in the circuit, $I=\frac{10 E}{10 r}=\frac{E}{r}$
Potential difference across 3 cells,
$$
V=I \times(3 r)=\frac{E}{r} \times 3 r=3 E
$$
Hence, ideal voltmeter will read $3 E$.
Total resistance of 10 cells $=10 \mathrm{r}$
$\therefore$ Current in the circuit, $I=\frac{10 E}{10 r}=\frac{E}{r}$
Potential difference across 3 cells,
$$
V=I \times(3 r)=\frac{E}{r} \times 3 r=3 E
$$
Hence, ideal voltmeter will read $3 E$.
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