question_answer

In the adjoining figure, the emf of the cell is 1.8 V and the internal resistance is \[(2/3)\Omega .\] The current in \[3\Omega \] resistance is:

A) 0.4 A

B) 0.8 A

C) 0.2 A

D) 0.1 A

Correct Answer: A

Solution :

\[8\Omega \] and \[2\Omega \] are in parallel and similarly \[6\Omega \] and \[4\Omega \] are also in parallel combination

\[\therefore \]Equivalent circuit is shown below

0.9 is divided in ratio\[\frac{1}{3}:\frac{1}{4}:\frac{1}{6}\]

\[{{I}_{1}}:{{I}_{2}}:{{I}_{3}}=\frac{1}{3}:\frac{1}{4}:\frac{1}{6}\]

\[{{I}_{1}}=\frac{\frac{1}{3}}{\frac{1}{3}+\frac{1}{4}+\frac{1}{6}}\,\,\times \,\,I=0.9\,\,\times \,\,\frac{1}{3\times \frac{4+3+2}{12}}\]\[=\frac{0.9}{3}\times \frac{12}{9}=0.4A\]