Capacitor types in electronics: which of the following capacitor constructions is polarized (has a required +/− orientation)?

Introduction / Context:
Polarized capacitors must be connected with the correct polarity because their dielectric structure relies on a formed oxide layer that fails if reverse-biased. Knowing which capacitor families are polarized is essential for safe PCB design and power-supply filtering.

Given Data / Assumptions:

• Options include common capacitor types used in electronics.
• We assume ideal, general-purpose parts (no specialized non-polar electrolytics).
• Question asks which construction is inherently polarized.

Concept / Approach:
Electrolytic capacitors (aluminum or tantalum) are normally polarized because the dielectric is a thin oxide grown on the anode foil; reverse voltage can damage or destroy them. By contrast, mica, ceramic, and plastic-film capacitors use solid dielectrics that are normally non-polarized and can be connected either way in DC circuits.

Step-by-Step Solution:

Verification / Alternative check:
Datasheets show polarity stripe and maximum reverse voltage ~0 V for standard electrolytics; non-polar electrolytics exist but are explicitly labeled as such and are not implied here.

Why Other Options Are Wrong:

• Mica: stable, non-polar dielectric.
• Ceramic: Class 1 and Class 2 types are non-polarized.
• Plastic-film: polypropylene, polyester, etc., are non-polarized.
• None of the above: incorrect because electrolytic is polarized.

Common Pitfalls:

• Assuming all capacitors can be reversed; electrolytics usually cannot.
• Confusing specialized non-polar electrolytics with standard polarized parts.

Final Answer:
electrolytic