
$\therefore 4 i _1+2\left( i _1+ i _2\right)-3+4 i _1=16\, V$
Using Kirchhoff's second law in the closed loop we have
$9-i_2-2\left(i_1+i_2\right)=0$
Solving equations $(i)$ and $(ii)$, we get $i _1=1.5 A ^{\text {and } i _2}=2 A$
$\therefore$ current through $2 W$ resistor $=2+1.5=3.5\,A$.

(Given resistivities of iron and copper-nickel alloy wire are $12 \;\mu \Omega {cm}$ and $51\; \mu \Omega {cm}$ respectively) (in ${m}$)
| Column $- I$ | Column $- II$ |
| $(A)$ Drift Velocity | $(P)$ $\frac{m}{n e^{2} \rho}$ |
| $(B)$ Electrical Resistivity | $(Q)$ $\mathrm{ne} v_{\mathrm{d}}$ |
| $(C)$ Relaxation Period | $(R)$ $\frac{\mathrm{eE}}{\mathrm{m}} \tau$ |
| $(D)$ Current Density | $(S)$ $\frac{E}{J}$ |


Reason : Resistance of wire is proportional ot resistivity of material.