Question

As the switch $S$ is closed in the circuit as shown in figure, current passed through it is

• A. $4.5A$
• B. $7.5A$
• C. $3.0A$
• D. $0$

Answer 1

The correct option is A

$4.5A$

Let $V$ be the potential of the junction as shown in figure.

Applying junction law, we have

$\frac{20-V}{2}+\frac{4-V}{4}=\frac{V-0}{2}$

$40–2V+4–V=2V$

$5V=44$ $\Rightarrow$ $V\approx 9V$

$i=\frac{V}{2}=4.5A$