Power-supply filtering terminology (duplicate repaired for consistency): In rectifier-based DC supplies, the small AC component superimposed on the DC output is commonly referred to as what?

Introduction / Context:
Even with filtering, rectifier outputs retain a periodic residue of the original AC. Correctly naming this artifact is essential when interpreting datasheets and specifying power-supply performance. This item mirrors a common textbook definition to reinforce vocabulary.

Given Data / Assumptions:

• A rectifier and filter network produce a DC output that is not perfectly flat.
• The residual periodic component is small compared to the DC level.
• We are asked for the standard term used by engineers.

Concept / Approach:
The small, periodic variation superimposed on the DC output is called ripple. It is quantified as Vr(pp) (peak-to-peak ripple) or a percentage of the DC level. Ripple frequency depends on rectifier topology: full-wave produces ripple at twice the mains frequency, half-wave at the mains frequency. Filters (C, RC, LC, or regulators) reduce ripple magnitude.

Step-by-Step Solution:

Verification / Alternative check:
Observing the supply on an oscilloscope shows a DC level with a small, periodic waveform—the ripple—riding atop it. Power-supply datasheets specify “ripple and noise.”

Why Other Options Are Wrong:

• Pulsating dc: Describes unfiltered rectifier output before smoothing.
• Trickle: Refers to low charging current, not output AC residue.
• Waffle / ringing: Not the standard term; ringing is a transient phenomenon, not steady periodic residue.

Common Pitfalls:
Confusing ripple with random high-frequency noise; both can coexist but are characterized and mitigated differently.

Final Answer:
ripple