question_answer

The value of current I in the circuit shown in the

A)  0.2 A                                    

B)  0.8 A

C)  1.5 A                                    

D)  2.4 A

Correct Answer: B

Solution :

                 The given circuit consists of three resistors \[{{R}_{2}},{{R}_{3}}\] and \[{{R}_{4}}\] in series while \[{{R}_{1}}\] is connected in parallel to their equivalent. \[\therefore \]  \[R={{R}_{2}}+{{R}_{3}}+{{R}_{4}}\]                 \[=5\,\Omega +5\,\Omega +5\,\Omega =15\,\Omega \] \[\therefore \]  \[\frac{1}{R}=\frac{1}{R}+\frac{1}{{{R}_{1}}}=\frac{1}{15}+\frac{1}{5}\]                 \[\Rightarrow \]               \[R=3.75\,\Omega \]                 \[I=\frac{V}{R}=\frac{3}{3.75}=0.8\,A\]