Question T6D06
From subelement T6 - T6D
What component changes 120 V AC power to a lower AC voltage for other uses?
Why is this correct?
A transformer changes 120V AC power to lower AC voltage through electromagnetic induction using two coils around an iron core. Variable capacitors store energy and tune circuits but don't change voltage. Transistors amplify signals but don't convert AC voltage levels. Diodes rectify AC to DC but don't reduce voltage levels—they only control current direction.
Memory tip
Remember transformers by their function: they 'transform' voltage levels while keeping the same frequency. Look for questions asking about voltage conversion between different AC levels—transformers are always the answer for AC-to-AC voltage changes, while other components serve different purposes.
Learn more
Transformers operate on mutual inductance between primary and secondary windings. The voltage ratio equals the turns ratio: if the secondary has half the turns of the primary, output voltage is halved. This principle enables power supply design, impedance matching between transmission lines and antennas, and audio circuit interfacing. Understanding turns ratios helps explain why transformers are essential for matching different voltage requirements in amateur radio station equipment and accessories.
Think about it
Why do you think transformers can only work with AC voltage and not DC voltage?