Reluctance Notes & Topics for GATE EE/IES/ISRO/BARC 2019

By BYJU'S Exam Prep

Updated on: September 25th, 2023

In this article, you will find the Study Notes on Inductance which will cover the topic as Introduction, Reluctances in Series and Reluctances in Parallel.

Magnetic circuits are analogous to resistive electronic circuits if we define the magnetomotive force (MMF) analogous to the voltage (EMF). The flux then plays the same role as the current in electronic circuits so that we define the magnetic analogue to resistance as the reluctance (R).



R = MMF/ Φ

R is proportional to the reciprocal of the inductance.

The reluctance of a uniform gap, without leakage, is, therefore:


Calculation of the electrical resistance of a wire or bar of uniform cross-section:


whereσ is the wire material conductivity, l the length and A is the wire cross-sectional area.

Req. = R1 + R2 + R3 +…

Reluctances in Series: The combination of reluctances in series, with a common flux-path, results in:

Reluctances in Parallel: Flux in a magnetic circuit may flow in various leakage paths, as well as the useful one. It can be shown, by considering two parallel flux-paths, with flux driven by the same mmf, that the equivalent reluctance for two reluctances in parallel is:


All the Best.

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