What describes an air core transformer?

An air core transformer is characterized primarily by the absence of magnetic material within its core. It utilizes air as the medium through which the magnetic field is generated, which distinguishes it from transformers that employ iron or other ferromagnetic materials to enhance magnetic coupling. This design is significant because the lack of a magnetic core means that the transformer operates with lower efficiency compared to those with iron cores, primarily due to lesser magnetic flux concentration. Additionally, air core transformers are often used in specialized applications, such as radio frequency (RF) circuits, where the absence of a core reduces losses and maintains a more linear response in high-frequency applications.

The other descriptors do not accurately apply to an air core transformer: it does not involve an iron core, does not specifically relate to voltage reduction directly, nor is it inherently designed for heavy loads as it is typically low in power capacity.