What device is used to step up or step down the voltage through mutual inductance?

The device that is utilized to step up or step down voltage through the principle of mutual inductance is the transformer. A transformer operates based on the relationship between the primary and secondary windings of wire around a magnetic core. When alternating current passes through the primary winding, it creates a varying magnetic field in the core, which then induces a voltage in the secondary winding.

This process allows for efficient voltage conversion; by adjusting the number of turns in the primary versus the secondary winding, the transformer can either increase (step up) or decrease (step down) the voltage level. This functionality is critical in various applications, particularly in power distribution systems, where transforming high voltages for efficient transmission and lower voltages for safe consumption is essential.

While capacitors, inductors, and resistors are fundamental components in electrical circuits, they do not perform the specific function of changing voltage levels through mutual inductance like transformers do. Capacitors store electrical energy, inductors resist changes in current, and resistors limit the flow of electric current, all of which are different roles in circuit design. Thus, the transformer is uniquely suited for the task described in the question.