Question

The correct combination of three resistances $1\,\Omega$, $2\,\Omega$ and $3\,\Omega$ to get equivalent resistance $\frac{11}{5}\Omega$ is

• A. All three are combines in parallel
• B. All three are combine in series
• C. $1\,\Omega$ and $2\,\Omega$ in parallel and $3\,\Omega$ is in series to both
• D. $2\,\Omega$ and $3\,\Omega$ are combined in parallel and $1\,\Omega$ is in series to both

Answer 1

Answer: (D)

According to option $2\,\Omega$ and $3\,\Omega$ are combined in a parallel combination. Hence equivalent resistance
$\frac{1}{R'}=\frac{1}{2}+\frac{1}{3}=\frac{5}{6}$
$\therefore R'=\frac{6}{5}$
$R'$ is combined in series to $1\,\Omega$
$\therefore R_{eq}=R'+1=\frac{6}{5}+1$
$=\frac{6+5}{5}=\frac{11}{5}\Omega$