On what principle does a transformer operate?

A transformer operates on the principle of electromagnetic induction. This principle states that when a conductor is placed within a changing magnetic field, an electromotive force (EMF) is induced in the conductor. In the context of a transformer, this involves two coils of wire (the primary and secondary windings) that are placed near each other but are not electrically connected.

When an alternating current passes through the primary winding, it creates a changing magnetic field around it. This magnetic field then induces an EMF in the secondary winding, which is physically located in proximity to the primary winding. The amount of voltage induced in the secondary can be adjusted based on the number of turns in each winding, allowing for voltage transformation, whether stepping up or stepping down.

Understanding this principle not only illustrates how transformers function in electrical applications but also highlights the importance of electromagnetic principles in many electrical devices. The other choices, though related to different physical phenomena, do not apply to the operation of a transformer. Heat conduction pertains to the transfer of thermal energy, pressure difference relates to fluid mechanics, and electrical capacitance deals with the ability of a system to store charge, none of which are relevant to how transformers operate.