Thousand cells of same emf $E$ and same internal resistance $r$ are connected in series in same order without an external resistance. The potential drop across $399$ cells is found to be ......... $E$
A$0$
B$399$
C$601$
D$1000$
Medium
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A$0$
a (a)
Current through the circuit $i=\frac{1000 E}{1000 r}=\frac{E}{r}$
Potential drop across one cell $=E-i r=E-\left(\frac{E}{r}\right) r=0$
$\Rightarrow$ For $399$ cells, total potential drop is zero
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