Two cells, $e.m.f.$ of each is $E$ and internal resistance $r$ are connected in parallel between the resistance $R$. The maximum energy given to the resistor will be, only when
A$R = r/2$
B$R = r$
C$R = 2r$
D$R = 0$
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A$R = r/2$
a (a) For maximum energy, we have External resistance of the circuit
$=$ Equivalent internal resistance of the circuit i.e. $R = \frac{r}{2}$
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