Four ammeters with identical internal resistance $r$ and a resistor $R$ are connected to a current source as given. if reading of $A_1$ and $A_2$ is $3\ A$ and $5\ A$ respectively then the reading $A_4$ is ............. $A$
A$1$
B$3$
C$5$
D$7$
Medium
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D$7$
d $\mathrm{V}_{1}=5 \mathrm{\,r}$
$\mathrm{V}_{2}=3 \mathrm{\,r}$
$\mathrm{V}_{1}-\mathrm{V}_{2}=2 \mathrm{\,r}$
curront in middle one is $2 \mathrm{\,A}$ so reading should be $7 \mathrm{\,A}$
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