What material is typically used for the transformer core?

The material typically used for the transformer core is iron. Iron is chosen because it has excellent magnetic properties that enhance the efficiency of the transformer. The core needs to have high permeability to allow magnetic field lines to pass through with minimal resistance, which iron provides. This property helps to effectively transfer electrical energy between the primary and secondary windings of the transformer through electromagnetic induction. The use of iron, often in various forms such as silicon steel, minimizes energy losses, such as hysteresis losses, when the magnetic field alternates, making it an ideal choice for transformers.

Other materials listed, such as copper, plastic, and rubber, do not have the required characteristics for a transformer core. Copper is primarily used for the windings due to its excellent conductivity, while plastic and rubber are insulators and would not support the necessary magnetic function required in a transformer core.