a$)$ In the circuit given below, the switch $S_1$ is opened and the switch $S_2$ is closed at $t=0.$ The switch $S_1$

$10$ was closed for a long time before it is opened. Find the current $i_2(t)$

b$)$ For the following lauuer metwork nul $\frac{v_2}{v_1},\frac{r_1}{v_1}$ and $v_{\frac{2}{11}}$

$10$