Dielectric comparison: Among air, mica, glass, and paper, identify the capacitor dielectric with the highest typical dielectric constant.
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Aair
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Bmica
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Cglass
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Dpaper
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E
Answer
Correct Answer: glass
Explanation
Introduction / Context:Dielectric materials determine a capacitor’s capacitance for a given geometry. A higher dielectric constant (relative permittivity) allows more charge storage at the same voltage, enabling physically smaller capacitors for the same value.
Given Data / Assumptions:
- Dielectrics listed: air, mica, glass, paper.
- Compare typical relative permittivity ranges used in general-purpose capacitors.
Concept / Approach:Relative permittivity (epsilon_r) indicates how much the dielectric increases capacitance compared to vacuum. Typical values: air ~ 1, paper ~ 2–3, mica ~ 5–7, many glasses ~ 5–10 (and specialized glasses even higher).
Step-by-Step Solution:Identify approximate ranges: air ≈ 1paper ≈ 2–3mica ≈ 5–7glass ≈ 5–10 (or higher depending on composition)Highest among given standard choices is glass.
Verification / Alternative check:Reference component data sheets: general-purpose glass dielectrics often outpace mica and paper in epsilon_r, explaining compact high-value glass capacitors and feedthrough designs.
Why Other Options Are Wrong:
- air: Lowest epsilon_r (~1), used mainly where minimal dielectric loading is desired.
- mica: Stable and low-loss, but typical epsilon_r below common glasses.
- paper: Lower epsilon_r than mica and glass.
Common Pitfalls:Confusing dielectric constant with breakdown voltage or loss tangent. A higher dielectric constant does not automatically mean better for all applications; losses and stability also matter.
Final Answer:glass