Use of electrolytic capacitors — polarity and waveform suitability An electrolytic capacitor (single polarized unit) is suitable for use with which type of applied voltage?

Introduction / Context:
Electrolytic capacitors provide very high capacitance per volume due to their electrochemical construction. However, they are polarized devices and their safe, correct use depends on maintaining the proper polarity across their terminals.

Given Data / Assumptions:

• Single, polarized aluminum or tantalum electrolytic capacitor.
• Standard dielectric formed by anodization (oxide layer) on the anode foil.
• No special non-polar or back-to-back configuration implied.

Concept / Approach:
Because the dielectric is created on one electrode, reversing the polarity or applying significant alternating voltage can degrade or break down the oxide, causing leakage current, heating, gas generation, or catastrophic failure. Therefore, a single polarized electrolytic is intended for DC (or ripple on a DC bias that keeps the correct polarity). Pure AC or high-frequency AC without DC bias is unsuitable unless a non-polar electrolytic or two back-to-back polarized units are used.

Step-by-Step Solution:
Identify that a polarized electrolytic requires a defined positive terminal.Recognize that AC alternates polarity, violating this requirement.Conclude: use with DC (including small AC ripple superimposed on proper DC bias).Therefore, select “dc only”.

Verification / Alternative check:
Datasheets specify maximum ripple current and minimum DC bias for AC ripple; non-polar electrolytics exist specifically for AC coupling in audio where needed.

Why Other Options Are Wrong:
AC only or high-frequency AC risks dielectric damage and failure; “both ac and dc” is only valid for non-polar types or special series configurations.

Common Pitfalls:
Using polarized capacitors in coupling networks without DC bias; ignoring polarity markings.

Final Answer:
dc only