Physics - Current Electricity Question with Solution | TestHub

$R_{eq}$ for mixed series and parallel combination of

  given circuit $R_{eq}=\frac{1}{{\displaystyle \frac{1}{4R}}+{\displaystyle \frac{1}{4R}}}+R+\frac{1}{{\displaystyle \frac{1}{6R}}+{\displaystyle \frac{1}{12R}}}+R$

${\mathrm{R}}_{\mathrm{e}\mathrm{q}}=8\mathrm{R}$
Power dissipated by circuit $P=\frac{{\mathrm{V}}^2}{{\mathrm{R}}_{\mathrm{e}\mathrm{q}}}$
$\Rightarrow 4=\frac{{16}^2}{8\mathrm{R}}$
$\Rightarrow \mathrm{R}=\frac{256}{32}=8\mathrm{\Omega }$