Join 60,000+ competitive exam aspirants
or with email
Your Cart
SubtotalтВ╣0
TotalтВ╣0
Examoogle тАв User тАв info@examoogle.com тАв EE-2024-8821
Chapter 1 of 12 тАв Page 1 of 248ЁЯФТ Protected PDF тАв Watermarked
Join 60,000+ competitive exam aspirants
Which of the following inductor will have the least eddy current losses?
Air core
Laminated iron core
Iron core
Powdered iron core
Air core
Eddy current losses occur due to the circulation of induced currents in a conducting magnetic core when exposed to a time-varying magnetic field. Since an air core is non-conducting and lacks a magnetic material, it provides zero path for eddy current circulation, resulting in zero eddy current losses.
Eddy current losses occur due to the circulation of induced currents in a conducting magnetic core when exposed to a time-varying magnetic field. Since an air core is non-conducting and lacks a magnetic material, it provides zero path for eddy current circulation, resulting in zero eddy current losses.
PeтАЛ=KeтАЛBm2тАЛf2t2V тАФ where PeтАЛ is eddy current loss, KeтАЛ is a constant, BmтАЛ is max flux density, f is frequency, t is thickness, and V is volume.
According to Faraday's Law of Induction, a time-varying magnetic flux induces an EMF in any nearby conductor. In a solid iron core, this induced EMF generates circulating currents (eddy currents) that dissipate power as heat through I2R losses. By using an air core, the absence of a medium with finite conductivity (sigmaтЙИ0) prevents the formation of these parasitic currents.
Eddy current loss is directly proportional to the square of the frequency and the square of the material thickness.
Lamination of iron cores (Option B) reduces eddy current loss by breaking the conduction paths.
Air core inductors are ideal for high-frequency applications where core loss must be minimized.
Magnetic materials have high permeability but introduce hysteresis and eddy current losses.
Zero eddy current loss
Zero hysteresis loss
Excellent linearity (no saturation)
Low inductance per unit volume
Large size for high inductance values
Magnetic leakage and interference
RF tuning circuits
High-frequency filters
Antenna matching networks
| Feature | Core A | Core B |
|---|---|---|
Material | Air | Laminated Iron |
Eddy Current Loss | Zero | Low |
Option B (Laminated core) uses thin insulating sheets to minimize eddy current paths, but still experiences some losses.
Option C (Solid iron core) suffers from massive eddy current losses due to the large cross-sectional area of the conductor.
Powdered iron cores (Option D) use insulated magnetic particles to provide high permeability while restricting eddy current paths.
A is correct тАФ An air core inductor has no magnetic material to conduct induced eddy currents, hence it experiences zero eddy current losses.
Always remember that at very high frequencies, air-core inductors are preferred because the core-related losses (PhтАЛ+PeтАЛ) dominate as frequency increases.