$ \Rightarrow $ $x = \frac{{2.5}}{{(20 + 80 + 0)}} \times \frac{{20}}{{10}} = 5 \times {10^{ - 5}}\frac{V}{{mm}}$

$(A)$ $4$ if wires are in parallel
$(B)$ $2$ if wires are in series
$(C)$ $1$ if wires are in series
$(D)$ $0.5$ if wires are in parallel.


| 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 | $(S)$ $\frac{E}{J}$ |
