Question

Three pure inductances each of $3\text{H}$ are connected as shown in fig. The equivalent inductance between points $A$ and $B$ is

• A. $1\text{H}$
• B. $2\text{H}$
• C. $3\text{H}$
• D. $9\text{H}$

Answer 1

The correct option is A $1\text{H}$

The circuit is equivalent to three inductances, each of value $3\text{H}$ connected in parallel. The equivalent inductance $L^{\prime }$ is given by
$\frac{1}{L^{\prime }}=\frac{1}{L}+\frac{1}{L}+\frac{1}{L}=\frac{3}{L}=\frac{3}{3}=1$
or $L^{\prime }=1\text{H}$. Hence the correct choice is (a).