Final answer:
An transformer is an electrical device that transfers energy between two or more circuits through electromagnetic induction, without a direct electrical connection between windings. Transformers can either equalize, increase, or decrease voltages and often consist of primary and secondary coil windings surrounded by an iron core to enhance magnetic field confinement.
Step-by-step explanation:
An transformer has no direct electrical connection between the primary and secondary windings. This device operates on the principle of electromagnetic induction. The primary winding is connected to an alternating voltage source and creates a magnetic field within a core, which induces a voltage across the secondary winding. The properties of transformers vary; some transformers have an equal number of primary and secondary turns, while others are designed with different numbers of turns to increase or decrease the voltage, known as step-up or step-down transformers respectively.
A typical transformer symbol might indicate an iron core through which both windings are wound, yet they remain electrically isolated from each other. As shown in FIGURE 15.22, a step-up transformer has more turns in the secondary winding compared to the primary winding. In Figure 20.31, a laminated-coil transformer which also demonstrates Faraday's law of induction, has a magnetic field confined within an iron core, thereby enhancing the coupling between the windings and minimizing energy loss.