Resistance $n$, each of $r$ ohm, when connected in parallel give an equivalent resistance $R \mathrm{~ohm}$.…
Resistance $n$, each of $r$ ohm, when connected in parallel give an equivalent resistance $R \mathrm{~ohm}$. If these resistances were connected in series, the combination would have a resistance in ohms, equal to :
$n^2 R$
$\frac{R}{n^2}$
$\frac{R}{n}$
$n R$
Solution
According the question:
$\begin{aligned}
R & =\frac{r}{n} \\
\Rightarrow \quad r & =n R \\
\therefore \quad R \text { series } & =n r=n^2 R
\end{aligned}$