Electrical Workers Registration Board (EWRB) Theory Practice Test 2026 - Free EWRB Theory Practice Questions and Study Guide

The correct answer highlights the role of capacitors and inductors in smoothing the DC output of a rectifier.

Capacitors are essential in this process because they store electrical energy and release it when needed, effectively reducing voltage fluctuations and providing a more stable output. When connected to the output of a rectifier, they charge during the peaks of the rectified waveform and discharge during the valleys, thereby smoothing out the ripples and producing a smoother DC voltage.

Inductors, on the other hand, work by resisting changes in current flow. They can further help in smoothing the output by integrating the current over time, which reduces the overall ripple present in the DC output. When used in combination with capacitors, inductors can create an effective filter that significantly improves the quality of the DC output from a rectifier.

The other options involve components that serve different primary functions in electrical circuits. While transistors and Zener diodes are used for voltage regulation and switching applications, they do not primarily function to smooth rectified outputs. Resistors can potentially help in certain scenarios but are not as effective as capacitors and inductors for filtering purposes due to their tendency to dissipate energy as heat, which does not contribute to smoothing the voltage as efficiently.