Question

Figure shows three resistances are connected with switch S initially the switch is open. When the switch S is closed find the current passed through it

• A. $4.5A$
• B. $5A$
• C. $4A$
• D. $4.7A$

Answer 1

The correct option is A $4.5A$

Current when switchis open,

$I_{so}=\frac{20-5}{2+4}=\frac{15}{6}A$

Applying Kirchhoff's law,

$20+\frac{15}{6}\times 2-1-\frac{15}{6}\times 4-5=I_{sc}\left(2\right)$

$I_{sc}$ is the current through branch when switch is closed.

$25-16=2I_{sc}$

Hence,

$I_{sc}=4.5A$