Which of the following components is necessary for smoothing output in a power supply?

In a power supply, a capacitor plays a crucial role in smoothing the output. After rectifying the AC voltage into DC (which often results in a fluctuating voltage), a capacitor helps to smooth out these ripples in the voltage waveform. It charges during the peaks of the voltage and discharges during the dips, effectively providing a more stable and continuous output voltage.

The smoothing process is essential for various electronic devices, as they typically require a consistent DC voltage for proper operation. Capacitors are particularly effective in this application due to their ability to store and release electrical energy quickly, which helps to maintain a steady output voltage under varying load conditions.

While resistors can be used in power supplies for limiting current or forming voltage dividers, they do not contribute to smoothing. Inductors can also be used in power supplies, specifically in filtering applications but are not as common as capacitors in straightforward smoothing tasks. Transistors are essential for switching and amplifying signals in power supplies but do not directly smooth the output voltage.