Question

Find the equivalent inductance between $\text{A}$ and $\text{B}$ is-

• A. $3.66\text{H}$
• B. $9\text{H}$
• C. $0.66\text{H}$
• D. $1\text{H}$

Answer 1

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

Assigning potential to different nodes, we can reduce the given circuit as follows,



The equivalent inductance $L_{AB}$ is given by,

$\frac{1}{L_{AB}}=\frac{1}{L_1}+\frac{1}{L_2}+\frac{1}{L_3}=\frac{1}{3}+\frac{1}{3}+\frac{1}{3}=\frac{3}{3}=1\text{mH}$

$\therefore L_{AB}=1\text{mH}$

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}--> Hence, $\left(D\right)$ is the correct answer.

Why this question? This question recalls your concepts of circuits in series and parallel combination. Instead of resistors, we just have to consider combinations of indicators.