\(\frac{{{R_1}}}{{{R_2}}}\,\, = \,\,\frac{{{R_3}}}{{{R_4}}}\,\,\,\,\,\, \Rightarrow \,\,\,\frac{{6x}}{{(6 + x)}}\,\,\, = \,\,\,\,\frac{6}{3}\)
\(\therefore \,\,\,x\,\, = \,\,12\,\,\Omega \).
(કોપરની અવરોધકતા $=1.7 \times 10^{-8}\, \Omega \,{m}$, એલ્યુમિનિયમની અવરોધકતા $=2.6 \times 10^{-8}\, \Omega \,{m}$ લો)