As the switch $S$ is closed in the circuit shown in figure, current passed through it is .................. $A$
A$4.5$
B$6$
C$3$
D$0$
Diffcult
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A$4.5$
a (a) Let $V$ be the potential of the junction as shown in figure. Applying junction law, we have
or $\frac{{20 - V}}{2} + \frac{{5 - V}}{4} = \frac{{V - 0}}{2}$
or $40 -2\,V + 5 -V = 2\,V$ or $5\,V = 45 $ $==>$ $ V = 9\,V$
${i_3} = \frac{V}{2} = 4.5\,A$
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