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Examoogle • User • info@examoogle.com • EE-2024-8821
Chapter 1 of 12 • Page 1 of 248🔒 Protected PDF • Watermarked
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A crack in the magnetic path of an inductor will result in
Unchanged inductance
Increased inductance
Zero inductance
Reduced inductance
Reduced inductance
A crack or air gap in the magnetic core of an inductor introduces a region of very high reluctance in the magnetic circuit. Since inductance is inversely proportional to the total reluctance of the path, the addition of this gap results in a significant reduction in total inductance.
A crack or air gap in the magnetic core of an inductor introduces a region of very high reluctance in the magnetic circuit. Since inductance is inversely proportional to the total reluctance of the path, the addition of this gap results in a significant reduction in total inductance.
L=ℜN2 — Basic Inductance formula
ℜ=μAl — Reluctance formula
The inductance L of a magnetic circuit is given by L=RN2, where R is the reluctance. Reluctance is defined as R=μAl. An air gap introduces a segment with very low permeability μ0, which is significantly smaller than the core's permeability μc. This causes the total reluctance to increase drastically, thereby decreasing the overall inductance.
Magnetic air gaps (or cracks) increase the reluctance of the circuit.
Inductance is inversely proportional to the reluctance of the magnetic path.
The presence of a gap helps prevent magnetic saturation of the core.
Higher reluctance necessitates higher magnetizing current for the same flux.
Used intentionally in DC chokes to prevent core saturation.
Linearizes the B-H characteristic of the inductor.
Reduces the value of inductance for a given number of turns.
Increases fringing flux effects around the gap.
DC bias chokes in power electronics.
Flyback transformer core design.
In electrical machines, air gaps are necessary for mechanical clearance, but they necessitate more ampere-turns.
Option B is incorrect because inductance cannot increase when path reluctance is added.
Option A is incorrect as the magnetic path geometry is physically altered.
D is correct — A crack creates an air gap, which increases the total reluctance of the magnetic path and consequently reduces the inductance.
Always remember that an air gap 'breaks' the magnetic circuit's efficiency, acting like a resistor in an electrical circuit—it limits the flux, thus reducing the inductive property.