A transformer is used to _____ voltage in a circuit?

A transformer is a critical component in electrical circuits primarily used to increase or decrease voltage levels. This process is based on the principle of electromagnetic induction, where the primary coil of the transformer creates a magnetic field that induces a voltage in the secondary coil. By adjusting the number of turns in either coil, transformers can step up (increase) the voltage or step down (decrease) the voltage as needed for different applications.

This functionality is essential in various scenarios, such as in power distribution systems, where high voltages are used to transmit electricity over long distances efficiently, and transformers at substations lower the voltage for distribution to homes and businesses.

The other options do not accurately describe the primary purpose of a transformer. Stabilizing or altering voltage refers more to voltage regulators or stabilizers, whereas converting or rectifying voltage is associated with different devices like rectifiers. Isolating or combining is a function seen in certain types of electrical circuits but does not capture the primary role of a transformer in the context of voltage management.