Question

In the circuit shown in the adjoining diagram $E=10$ volts, $R_1=2$ ohms, $R_2=3$ ohms, $R_3=6$ ohms and $L=5$ henry. The current $i_1$ just after pressing the switch S is

• A. $2.5$ amp
• B. $2$ amp
• C. $\frac{5}{6}$ amp
• D. $\frac{5}{3}$ amp

Answer 1

Answer: (B)

$2$ amp

We know that current through an inductor is given by

$I=I_o(1-e^{-Rt/L})$

At $t=0,I=0$

Hence, when switch is just pressed, there will be no current through inductor containing wire.

Hence, $i_2=0$ and $i_1=i_3$

Now, $R_{eq}=R_1+R_2=5ohm$

Hence, current $i_1=\frac{E}{R_{eq}}$

$⟹i_1=\frac{10}{5}=2A$

Answer-(B)