A transformer works with what?

A transformer primarily works with electricity, specifically alternating current (AC). The functioning of a transformer is based on the principle of electromagnetic induction, which allows it to transfer electrical energy between two or more coils through a magnetic field. When an electric current passes through the primary coil, it generates a magnetic field that induces a current in the secondary coil. This process allows the transformer to increase (step-up) or decrease (step-down) voltage levels as needed while conserving power, making it an essential component in electrical systems for efficient voltage regulation.

The other choices, while relevant in the context of different physical phenomena, do not accurately describe the primary functioning of a transformer. Magnetism is indeed involved, but it is the relationship with electricity that is central to a transformer's operation. Heat and pressure do not play any direct role in the basic principle of how a transformer operates, as they pertain to different physical processes.