ARRL Technician Practice Exam

Which component is used to convert 120V AC house current to a lower AC voltage?

1. Capacitor

2. Transformer

3. Resistor

4. Inductor

The correct answer is: Transformer

The component that converts 120V AC house current to a lower AC voltage is a transformer. Transformers operate on the principle of electromagnetic induction and are designed specifically to change the voltage of alternating current. They consist of two coils of wire, the primary and secondary, wound around a magnetic core. The voltage can be increased or decreased depending on the ratio of the number of turns in the primary coil compared to the secondary coil. When the alternating current flows through the primary coil, it creates a magnetic field that induces a voltage in the secondary coil. If the secondary coil has fewer turns than the primary, the voltage is stepped down; if it has more, the voltage is stepped up. In residential and commercial applications, transformers are commonly used to adapt the voltage levels for various electrical appliances and systems safely. Other components, such as capacitors, resistors, and inductors, serve different functions in electrical circuits. A capacitor stores electrical energy temporarily, a resistor limits current flow, and an inductor stores energy in a magnetic field when electrical current passes through it. While these components are essential in different applications, they do not perform the voltage conversion task assigned to transformers.