
$\frac{\mathrm{V}_{\mathrm{AB}}}{\mathrm{V}_{\mathrm{AD}}}=\frac{\mathrm{V}_{\mathrm{BC}}}{\mathrm{V}_{\mathrm{CD}}} \Rightarrow \frac{12}{6+\mathrm{x}}=\frac{0.5}{0.5}$
$\mathrm{x}=6 \Omega$


$(i)$ The equivalent e.m.f. is smaller than either of the two $e.m.f.$ is
$(ii)$ The equivalent internal resistance is smaller than either of the two internal resistances


