Transformer coils are essential components in electrical transformers, which are devices used to change the voltage of alternating current (AC) electricity. These coils consist of wire wound around a core, typically made of iron or ferrite, and are divided into two types: primary and secondary coils. The primary coil receives electrical energy, while the secondary coil delivers it at a different voltage level. The operation of transformer coils is based on the principle of electromagnetic induction, where a changing magnetic field in the primary coil induces a voltage in the secondary coil. This process allows for efficient transmission of electricity over long distances, making it crucial for power distribution systems and various applications in electronics and telecommunications.