question_answer

Two resistances of 10\[\Omega \] and 20\[\Omega \] and an inductor of inductance 5 H are connected to a battery of 2 V through a key K as shown in the figure. At time t = 0, when the key K is closed the initial current through the battery is

A)  \[0.2\,A\]                          

B)  \[\frac{2}{15}\,A\]

C)  \[\frac{1}{15}\,A\]                         

D)  Zero

Correct Answer: C

Solution :

                 The induction will oppose the flow of current thus, the current can flow through the path ABCDEFGH                 Now, \[10\,\,\Omega \] and \[20\,\,\Omega \] resistors are in series Their equivalent resistance \[=10\,\,\Omega +20\,\,\Omega \]                                                                 \[=30\,\Omega \] Current (I) \[=\frac{V}{R}=\frac{2}{30}=\frac{1}{15}A\]