For efficiency, what type of construction is preferred for transformer cores?

The preferred construction for transformer cores is laminated sheets of metal because this design significantly reduces energy losses that occur due to eddy currents. When a magnetic field is applied to a conductor, it can induce currents that circulate within the conductor itself, leading to energy dissipation as heat. By using laminated sheets, the core acts as a series of thin, electrically insulated layers, which helps to restrict the flow of these eddy currents and thus enhances the overall efficiency of the transformer.

Additionally, laminating the cores can minimize the hysteresis losses associated with the magnetic properties of the material. This means that the core material can switch magnetization states more effectively with less energy loss. Therefore, the laminated sheet design strikes an excellent balance between magnetic performance and energy efficiency, making it the optimal choice for transformer cores.