Which statement correctly describes how to reduce both hysteresis loss and eddy current loss in magnetic cores?

• A. Hysteresis loss depends on material and frequency; eddy current loss depends on conductivity and thickness; reduce with laminated cores, lower conductivity materials, higher resistivity, or grain-oriented steels.
• B. Hysteresis loss depends only on temperature; eddy current loss depends only on geometry.
• C. Hysteresis loss depends on mass of core; eddy current loss depends on operating voltage.
• D. Hysteresis loss is independent of frequency; eddy current loss is independent of conductivity.

Answer: (A)

When you want to cut both hysteresis loss and eddy current loss in magnetic cores, you need to manage how each loss mechanism responds to material properties, frequency, and how the core is built. Hysteresis loss is tied to the area of the magnetization (B–H) loop and increases with frequency; choosing a material with a small, narrow hysteresis loop (low coercivity) reduces this loss, and the frequency of operation amplifies it. Eddy current loss comes from currents induced in the conductive paths of the core as the flux changes; it grows with the material’s conductivity (or inversely with resistivity), with the thickness of the conducting paths, and with frequency.

Design practices that address both losses include laminating the core (thin insulated sheets) to interrupt eddy current paths, using materials with lower conductivity or higher resistivity to further reduce eddy currents, and employing grain-oriented steels that offer favorable magnetic properties (low losses) while also benefiting from the laminated structure. This combination directly targets the causes of both losses.

The other statements either oversimplify or misstate the dependencies (for example, hysteresis is not determined only by temperature, and eddy currents are not determined only by geometry or by mass/voltage alone), so the approach described here is the most accurate.