Properties of Ferrites: Identify the correct characteristic of ferrite materials commonly used in transformers and inductors.
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Alow copper loss
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Blow eddy current loss
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Clow resistivity
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Dhigher specific gravity compared to iron
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Ehigh thermal conductivity
Answer
Correct Answer: low eddy current loss
Explanation
Introduction / Context:Ferrites are ceramic compounds consisting of iron oxide mixed with other metallic elements. They are widely used in RF transformers, inductors, and high-frequency applications because of their unique electrical and magnetic properties.
Given Data / Assumptions:
- Ferrites are magnetic oxides with high electrical resistivity.
- Used where eddy current suppression is required.
Concept / Approach:
Eddy current loss arises from circulating currents in conductive cores when exposed to alternating magnetic fields. Ferrites, with high resistivity, significantly suppress eddy currents, making them ideal for high-frequency use.
Step-by-Step Solution:
Step 1: Copper loss is irrelevant for ferrite.Step 2: Ferrites have high resistivity → so 'low resistivity' is incorrect.Step 3: Density of ferrites is lower than iron, so 'higher specific gravity' is wrong.Step 4: Correct property is 'low eddy current loss.'Verification / Alternative check:
Ferrite cores in SMPS confirm reduced eddy current heating vs. iron cores.
Why Other Options Are Wrong:
- Low copper loss: not relevant.
- Low resistivity: false, ferrites have high resistivity.
- Higher specific gravity: false, ferrites are lighter.
Common Pitfalls:
- Confusing conductivity with resistivity.
- Assuming all magnetic cores suffer large eddy currents.
Final Answer:
low eddy current loss