Which of the following components is essential in smoothing out DC output from a power supply?

The component that is essential in smoothing out DC output from a power supply is the capacitor. In power supplies, especially those that convert AC to DC, capacitors are used to filter the output. After rectification, the DC voltage can have ripples due to variations in the input AC signal and the switching characteristics of the rectifier.

Capacitors store electrical energy temporarily and release it when there is a drop in voltage, thereby reducing these ripples and providing a more stable and smoother DC output. The larger the capacitance, the more charge the capacitor can store and the better it can smooth out fluctuations in the voltage level.

Other components mentioned, such as resistors, diodes, and transformers, play different roles in the power supply circuit. Resistors are generally used for limiting current and voltage drops. Diodes are crucial for rectification, allowing current to flow only in one direction, but they do not smooth the output; their primary function is to convert AC to DC. Transformers are utilized to step up or step down AC voltages and do not directly contribute to the DC smoothing process.

Therefore, the capacitor is pivotal in ensuring that the DC output remains as stable and smooth as possible after conversion from an AC source.