To overcome power loss due to hysteresis and eddy currents, an AC series motor frame is made from ____________ iron.

The correct answer is laminated iron. Laminating the iron used in an AC series motor frame is crucial because it significantly reduces power losses attributed to hysteresis and eddy currents.

Eddy currents are loops of electrical current that can form within conductors when exposed to changing magnetic fields, leading to energy loss in the form of heat. Similarly, hysteresis loss occurs due to the lagging of magnetic flux density behind the magnetizing force in magnetic materials. By using laminated iron, manufacturers can minimize these losses because the thin layers of iron (laminations) are insulated from each other. This insulation restricts the flow of eddy currents, reducing their intensity and therefore minimizing energy loss.

In contrast, cast iron, solid iron, and coated iron options do not provide the same level of efficiency for reducing losses. Cast iron and solid iron do not offer the insulation required between layers to control eddy currents effectively, while a coating alone does not address the underlying problems of hysteresis and eddy current losses. Thus, laminated iron is the preferred choice for optimizing the efficiency of AC series motors.