Physics - Current Electricity Question with Solution | TestHub

In the given circuit, resistors$4R$and$2R$are connected in parallel while resistance$R$is connected in series to it.

Hence, equivalent resistance is, of parallel combination
$\frac{1}{R^{\prime }}=\frac{1}{4R}+\frac{1}{2R}$

${\stackrel{}{\Rightarrow }}^{}$$R\text{'}=\frac{8}{6}R$$=\frac{4}{3}R$

$⟹{R"}^{}=R+\frac{4}{3}R=\frac{7R}{3}$(series combination)

Given, emf is E volts, thereforeusing ohm's law,

$i=\frac{E}{R^{\mathrm{\text{'}\text{'}}}}=\frac{3E}{7R}$
Potential difference across R is

$V=ir=\frac{3E}{7R}\times R=\frac{3E}{7}$

Potential difference across 2R is

$V^{\prime }=E-\frac{3E}{7}=\frac{4E}{7}$