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Difficulty: EasyInductors and Transformers

A technician is assembling a low-pass filter circuit and connects two inductors in series with values of 45 mH45\text{ mH} and 80 mH80\text{ mH}. Assuming there is no mutual magnetic coupling between the coils, what is the total equivalent inductance of the circuit in millihenries (mH\text{mH})?

Answer: 125 mH

Answer

125
When inductors are connected in series without mutual inductance, their magnetic opposition to current changes accumulates directly, meaning the total inductance is simply the sum of the individual inductances (45 mH+80 mH=125 mH45\text{ mH} + 80\text{ mH} = 125\text{ mH}).

Step-by-Step Solution

1
Recall the formula for combining series inductances without mutual magnetic coupling.
Ltotal=L1+L2L_{\text{total}} = L_1 + L_2
Like series resistors, total series inductance is the direct sum of individual inductances when there is no magnetic interaction.
2
Add the two individual inductance values together.
45 mH+80 mH=125 mH45\text{ mH} + 80\text{ mH} = 125\text{ mH}
Direct addition provides the equivalent total inductance in millihenries.

Key Concept

Inductors in series combine by direct addition, identical to the rule for resistors in series.
Estimated Time:45s
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Topics

Inductors and Transformers

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