Some of the motor windings are heavy metals, such as rods or plates of metal, usually copper, that perhaps it is aluminum, these motors are typically powered by electromagnetic induction.
Some motor coil is thicker than metal. Such as a bar or a metal plate, usually copper, aluminum, sometimes these motors are usually driven by the electromagnetic induction.
Some motor coil metal is very thick. Such as bars or metal sheet is usually copper, sometimes, aluminium, these motors normally is driven by electromagnetic induction.