What is the primary purpose of toroid cores in transformers?

The primary purpose of toroid cores in transformers is to concentrate the magnetic flux. Toroidal cores are shaped like a doughnut, which allows for a more efficient path for the magnetic field created by the current flowing through the windings of the transformer. This design minimizes the air gap, leading to a higher magnetic coupling between the primary and secondary windings.

By concentrating the magnetic flux within the core, toroidal designs also help reduce electromagnetic interference and losses due to leakage flux compared to other core shapes. This improved efficiency leads to better performance in applications where space and energy efficiency are crucial.

The other options consider different aspects that are not the main function of a toroidal core. While they may relate to various transformer characteristics, they do not define the core's primary purpose effectively. Concentrating magnetic flux is essential for transformer operation, making toroidal cores a preferred choice in many designs.