Series inductance calculation: Three inductors of 15 mH each are connected in series. What is the total inductance?

Introduction / Context:
Inductors in series add directly, similar to resistors in series. This provides a simple way to obtain a higher total inductance for filters, chokes, and timing networks.

Given Data / Assumptions:

• Three inductors, each 15 mH.
• All three are connected in series.
• Ideal components with negligible coupling.

Concept / Approach:

For series inductors (with negligible mutual coupling), L_total = L1 + L2 + L3. Units must be consistent (millihenry here).

Step-by-Step Solution:

Verification / Alternative check:

If series inductors had coupling, mutual inductance M terms would affect the result. With ideal, un-coupled coils, simple addition applies.

Why Other Options Are Wrong:

30 mH implies only two coils added. 15 mH implies one coil. 5 mH is unrelated to series addition.

Common Pitfalls:

Confusing series with parallel behavior; ignoring mutual coupling in real layouts (not part of this ideal problem).

Final Answer:

45 mH