How is the equivalent inductance for n inductors in series calculated?

• A. Leq = 1/[(1/L1) + (1/L2) + ... + (1/Ln)]
• B. Leq = L1 + L2 + ... + Ln
• C. Leq = (L1 * L2) / (L1 + L2)
• D. Leq = L1 * L2 * ... * Ln

Answer: (B)

The equivalent inductance for inductors connected in series is calculated by simply adding the individual inductances together. This is based on the principle that when inductors are placed in series, the total magnetic field created by the inductors is the sum of the magnetic fields of each inductor. Consequently, the total inductance is determined by summing all the inductance values.

This relationship can be expressed mathematically as:

Leq = L1 + L2 + ... + Ln

This equation signifies that the effective inductance of the series configuration increases with the addition of each inductor. Each inductor contributes to the total inductive effect, leading to an increase in the overall opposition to changes in current. This concept is fundamental in circuit analysis, particularly when designing inductive filters and other similar applications where inductors are employed in series configurations.