What types of devices typically use capacitors?

Capacitors are commonly found in a variety of electronic devices due to their ability to store and release electrical energy. In motors, capacitors play a critical role in starting and running the motor by creating a phase shift necessary for the motor's operation, especially in single-phase induction motors. In power supplies, capacitors are used for smoothing out voltage fluctuations, maintaining a steady output, and filtering noise from the power signal. They also serve essential functions in radios, such as tuning circuits, where they help select the desired frequency by forming resonant circuits with inductors.

The other options do not typically involve the use of capacitors in the same fundamental way. Fuses and relays have different operational principles, relying on mechanical and thermal devices rather than capacitive energy storage. Light bulbs primarily rely on resistive heating and do not utilize capacitors for their basic function of producing light. Transformers, while they may interact with capacitors in certain circuits, primarily operate on electromagnetic induction and do not inherently use capacitors for their fundamental operation. Thus, the first choice accurately reflects the devices that commonly incorporate capacitors for essential electrical functions.