【Daily Question】Question from Issue 20150807
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Participation reward: 2 Wealth. Reward for correct answer: 9 wealth. To reduce eddy current losses, the following methods can be used. A. Increase the magnetic permeability of the core. B. Increase the electrical resistivity of the core. C. Decrease the magnetic permeability of the core. D. Decrease the electrical resistivity of the core. New activities have started in the production area; the prizes are attractive, so hurry and participate: 【Production Over Summer】The production area has entered the “train during the hot summer days” mode
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To reduce eddy current losses, the following methods can be used. B. Increase the resistivity of the core
Choose B. To reduce eddy current losses, the method of (increasing the resistivity of the core) can be used.
Answer: B. Increase the resistivity of the core. Explanation: To reduce eddy current losses, in industry the core is often made by stacking many thin ferromagnetic conductive sheets (such as silicon steel sheets), with a thin layer of insulating paint applied to the surface of these sheets. When magnetic flux passes through the narrow cross-section of the thin sheets, eddy currents are confined to flow along some narrow loops within each sheet. The net electromotive force in these loops is low, and their length is large; moreover, due to the high resistivity of this thin-sheet material, eddy current losses can be significantly reduced. Therefore, laminated cores are widely used in AC motors and electrical appliances to reduce eddy current losses.
To reduce eddy current losses, method (B) can be used. A. Increase the magnetic permeability of the core B. Increase the resistivity of the core C. Decrease the magnetic permeability of the core D. Decrease the resistivity of the core
B. Increase the resistivity of the core.