The most energy-efficient transformer cores are constructed with which of the following materials?

The most energy-efficient transformer cores are constructed with cold rolled silicon strips or amorphous steel alloy strips because these materials have lower magnetic losses compared to other options. Cold rolled silicon steel is treated to enhance its electrical resistivity and reduce hysteresis losses, which occur when the magnetic field in the core is cycled during operation. Lower losses translate to higher efficiency, making these materials highly desirable for transformer design.

Amorphous steel alloys also contribute significantly to energy efficiency. They exhibit even lower core losses due to their non-crystalline structure, which minimizes eddy current formation and keeps losses at a minimum. This is a critical feature, particularly in large transformers where efficiency directly affects operational costs and performance.

In contrast, while copper strips are excellent conductors, they are not typically used for transformer cores as they do not have the same magnetic properties needed for efficient operation. Metal impregnated polymers and standard laminated steel strips may offer some advantages, but they do not match the energy efficiency provided by cold rolled silicon and amorphous steel alloys. The latter materials' ability to significantly reduce losses makes them the best choice for constructing transformer cores in energy-efficient applications.