Question

Three inductances are connected as shown in the figure. The equivalent inductance between A and b is

• A. 2.25 H
• B. 1.20 H
• C. 0.225 H
• D. 0.120 H

Hint:

Treat inductors like resistors: add in series and use the reciprocal rule in parallel.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept
Inductors in series add directly, and inductors in parallel combine like resistors in parallel.
Here two \( 0.7 \text{ H} \) inductors are in parallel and this pair is in series with \( 0.85 \text{ H} \).

Step 2: Parallel Combination
\( \dfrac{1}{L_p}=\dfrac{1}{0.7}+\dfrac{1}{0.7}=\dfrac{2}{0.7} \)
So \( L_p = 0.35 \text{ H} \).

Step 3: Series Combination
\( L_{eq}=L_p+0.85=0.35+0.85=1.20 \text{ H} \)

Step 4: Compare the options
The value \( 1.20 \text{ H} \) matches option (B).

Final Answer:
The equivalent inductance between A and B is 1.20 H. \[ \boxed{\text{(B) }\text{1.20 H}} \]