What is typically used to transfer energy between the primary and secondary coils in a transformer?

Transformers operate on the principle of electromagnetic induction, and the mechanism that transfers energy between the primary and secondary coils is the magnetic field. When an alternating current passes through the primary coil, it generates a magnetic field that encircles the coil and induces a magnetic flux in the core of the transformer. This magnetic flux then links to the secondary coil, inducing a voltage in it according to Faraday's law of induction.

The effectiveness of this energy transfer is heavily dependent on the design of the transformer and the materials used, with a core typically made of ferromagnetic material to enhance the magnetic field and minimize energy losses. The induced voltage in the secondary coil can be adjusted based on the number of turns in the primary and secondary coils, which determines the transformer’s voltage transformation ratio.

The other options, while relevant in different contexts, do not serve as the primary means of energy transfer in a transformer. Conductive wires are used to connect the coils to the external circuit but do not transfer energy between the coils themselves. An air gap would detract from the efficiency of the magnetic coupling, and dielectric materials are utilized for insulation purposes rather than for energy transfer.